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Title: Wireless sensors for enhancing food supply chain visibility
Creator: Karuppuswami, Saranraj
Date: 2019
Collection: Electronic Theses & Dissertations
Description: "The demand for providing safe and quality food from the farm to the plate had led to the development of sensor technologies for quality control and real-time end-to-end monitoring of food along the supply chain. These advanced sensors serve as the first line of defense against food-borne outbreaks, economically motivated adulteration, and food contamination preventing illness, deaths, huge economic losses and promotes global health and well-being. The key goal is to ensure that the food...
Show more"The demand for providing safe and quality food from the farm to the plate had led to the development of sensor technologies for quality control and real-time end-to-end monitoring of food along the supply chain. These advanced sensors serve as the first line of defense against food-borne outbreaks, economically motivated adulteration, and food contamination preventing illness, deaths, huge economic losses and promotes global health and well-being. The key goal is to ensure that the food reaching the fork meets the highest safety standards by promoting tamper-free sustainable practices along the food supply chain. Real-time food monitoring also prevents unnecessary wastage due to spoilage or good food being thrown out due to misconception of the labeled expiration date. In this dissertation, a number of RF passive wireless sensing approaches are presented that allows simultaneous tracking and quality monitoring of packaged food products as it moves along the supply chain. The end goal is to develop a low cost, long range, battery-free, and real time sensor tag which can detect multiple parameters of the packaged food simultaneously and at the same time provide the identification information. In order to realize a multi-functional sensor tag, a number of sensing approaches are developed targeting four different types of food related quality control challenges; Adulteration, Contamination, Wastage, and Spoilage. To identify and eliminate food adulteration, magnetoelastic based dielectric and viscosity sensors are developed. These hybrid sensors are shorter range sensors and a number of liquid food items such as milk and oil are characterized. A sensing approach that utilizes 3D printed RF sensors coupled to a microfludic channel for liquid profling by monitoring the dielectric constant is developed for food quality detection. Next, to prevent contamination, capacitance based short range inductor-capacitor (LC) tanks are developed. An interdisciplinary approach which is a confluence of carbohydrate coated nano particles capturing bacteria in liquid food with RF detection is developed. A common method to prevent wastage or spoilage is to detect and profile aroma emitted from food. Adsorption, absorption, and capillary condensation based short range as well as long range sensors that monitor the dielectric constant or the conductivity of the target food are developed. First, a short range capillary condensation based sensor is demonstrated for volatile profiling using a porous substrate and an LC tank. This is followed by demonstrating sensitivity and specificity of different thin-film coated short range sensors that detect vapors that are directly related to the spoilage index of the food. Finally, a long range passive sensor integrated with ID is demonstrated for detecting Ammonia in packaged food. The developed sensor is compatible with existing RFID infrastructure and is capable of digitizing the sensor information along with the identification information for transmission. Overall, the work demonstrates that a passive multi-modal sensor provides additional information about products moving across the supply chain transforming the tracebility-centric supply chain into a value-centric one with increased visibility and empowers the different stake holders with the quality information as the product moves along the supply chain."--Pages ii-iii.
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Title: Transmission timing modulation for information coding in energy-constrained wireless networks
Creator: Feng, Dezhi
Date: 2020
Collection: Electronic Theses & Dissertations
Description: The objective of this thesis is to develop a framework of transmission timing-based modulation framework for improving energy efficiency, security, and information transfer capacity in embedded wireless networks with very thin energy budgets. The key idea is to modulate both intra-PDU (Protocol Data Unit) and inter-PDU timing for addressing energy, security, and information transfer capacity in wireless embedded networks. As for energy efficiency, we developed a novel pulse position-coded PDU...
Show moreThe objective of this thesis is to develop a framework of transmission timing-based modulation framework for improving energy efficiency, security, and information transfer capacity in embedded wireless networks with very thin energy budgets. The key idea is to modulate both intra-PDU (Protocol Data Unit) and inter-PDU timing for addressing energy, security, and information transfer capacity in wireless embedded networks. As for energy efficiency, we developed a novel pulse position-coded PDU (PPCP) paradigm. The core idea is to encode a protocol data unit (PDU) in terms of the silence duration between two sets of delimiter pulses, whose positions are modulated based on the value of the PDU. This PPCP architecture achieves significant energy savings by using a lesser amount of bit/pulse transmissions, and by eliminating long multi-bit preambles and headers, which are normally used in traditional packets. The proposed multi-access pulse-based PDU scheme enables medium sharing among many sensor nodes without requiring per-PDU frame synchronization. As for security, we developed the concept of a novel chaotic pulse position coded protocol data unit (CPPCP) for secure embedded networking. The core idea of CPPCP is to encode a protocol data unit (PDU) with a wideband pulse train with chaotically-varied inter-pulse intervals. The architecture ensures communication security by introducing randomness between data symbols, noise-like frequency spectrum, and significant energy savings by using a smaller number of pulse transmissions compared to existing secure coding schemes such as Bluetooth Low Energy (BLE). Compared with the traditional key-based cryptographic techniques, CPPCP suppresses decipherable information by eliminating symbol periodicity. The mechanism can also be piggy-backed on traditional cryptography solutions to achieve higher levels of security. Finally, for enhancing the information transfer capacity, we developed a data packet position modulation (DPPM) paradigm. Packet transmissions in low duty cycle networks are often scheduled as TDMA slots, whose periodicity is determined based on application sampling requirements and the energy in-flow, often in the form of energy harvesting. The key idea of DPPM is to modulate the inter-packet spacing for coding additional information without incurring additional transmission energy expenditures. We first developed a have a DPPM based networking solution for single-hop transmit-only networks in which a number of low-energy nodes transmit data to an aggregator. The architecture is developed for a two-node point-to-point link, followed by a multipoint-to-point multi-access network. Detailed analytical and simulation models are developed to demonstrate the performance of a symmetric and an asymmetric version of DPPM.
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Title: Towards discrete-pulse-based networking and event detection architectures for resource-constrained applications
Creator: Das, Saptarshi (Graduate of Michigan State University)
Date: 2019
Collection: Electronic Theses & Dissertations
Description: "In this dissertation thesis, we develop a scalable and energy-efficient discrete-pulse-based networking architecture along with a Spiking-Neuron-based low-power detection framework for use in resource-constrained settings. Applications such as Structural Health Monitoring (SHM) using wireless sensor networks powered by ambient energy harvesting are particularly suited for such a framework. The key idea in pulse-based networking is to eschew unnecessary overhead as incurred in traditional...
Show more"In this dissertation thesis, we develop a scalable and energy-efficient discrete-pulse-based networking architecture along with a Spiking-Neuron-based low-power detection framework for use in resource-constrained settings. Applications such as Structural Health Monitoring (SHM) using wireless sensor networks powered by ambient energy harvesting are particularly suited for such a framework. The key idea in pulse-based networking is to eschew unnecessary overhead as incurred in traditional packet-based networking and encode only the essential information using small number of discrete pulses and their positions with respect to a synchronized time frame structure. The baseline pulse networking does not scale well with increase in network size. In order to ameliorate this, we develop a scalable time frame structure for use in applications with large network size while preserving the energy advantages of pulse networking. In addition, we stress the importance of judicious use of erratic energy availability in ambient energy harvesting powered systems. To that effect, we build energy-awareness syntaxes within the pulse networking framework for better utilization of energy resources in such systems. We also demonstrate the feasibility of pulse networking over a through-substrate ultrasonic link layer and the advantages thereof in terms of utilizing existing infrastructure and removing the need for radio retrofits. We explore how the protocol performance varies for an airplane stabilizer monitoring application powered by ambient vibration energy harvesting in different energy availability scenarios. Beyond this, we also develop a Spiking-Neuron-based low-power event pattern detection architecture and illustrate how this can be incorporated within a pulse-networked SHM system. The Spiking Neuron based architecture is evidenced to be simpler in terms of implementation but more efficient in terms of computation and energy usage, thus enabling in-situ detection even at intermediate nodes in the network and robust low-power event pattern detection immune to pulse drifts and errors."--Pages ii-iii.
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Title: Security and privacy in resource constrained wireless networks
Creator: Pongaliur, Kanthakumar Mylsamy
Date: 2012
Collection: Electronic Theses & Dissertations
Description: Wireless networks use radio waves as a communication medium which allows for faster and cheaper deployment. The networks being wireless, are out in the open, which makes them vulnerable to malicious users that can hinder their performance. Of the several types of wireless networks, we focus on security and privacy in wireless sensor networks (WSN) and cognitive radio mobile ad-hoc networks (CR-MANET). The devices in these networks are limited in resources such as energy, low power radio, etc....
Show moreWireless networks use radio waves as a communication medium which allows for faster and cheaper deployment. The networks being wireless, are out in the open, which makes them vulnerable to malicious users that can hinder their performance. Of the several types of wireless networks, we focus on security and privacy in wireless sensor networks (WSN) and cognitive radio mobile ad-hoc networks (CR-MANET). The devices in these networks are limited in resources such as energy, low power radio, etc. CR-MANET devices are mobile, requiring them to run on limited amount of energy supplied by batteries, and conserve energy by reducing communication cost using low power radios. In addition, sensor devices have limited storage and a slower CPU. The purpose of a WSN is to sense and report event occurrences, whereas a CR-MANET provides improved spectrum utilization.We studied three kinds of attacks on WSN. The first type of attack is on the source privacy of sensor nodes. This attack happens because an important characteristic of events detected by sensor devices is bound to the location of event occurrence that can be revealed by compromise of detecting sensor device's source privacy. Thus, protecting privacy of event detecting sensor device is of paramount importance for which we present an encryption based solution to protect source privacy under eavesdropping and node compromise attacks. The second type of attack by the malicious entity can be invasive in nature, which could possibly cause damage to the device, or can be passive as in side channel attacks. A comprehensive study of side channel attacks on WSN is presented, along with a process obfuscation technique. The third type of attack is on the propagation of data packet generated by the sensor device. The detected event data is sent to the base station. If a malicious entity is able to prevent such event reporting packets from reaching the base station and segregate the attack zone, it will be able to carry out its malicious activity without getting caught. To cover such scenarios, a proactive dynamic camouflage event generation solution is presented.CR-MANET devices sense for vacant licensed spectrum and improve its utilization in an opportunistic manner. Accurate licensed spectrum occupancy detection by a CR-MANET device is hampered by signal fading, hidden terminal problems, etc. Spectrum occupancy decision can be improved by cooperative spectrum sensing (CSS). However, CSS is made difficult by the presence of malicious users. The malicious users can have two goals: one is to disrupt the network, another is to manipulate the network for its own personal gains. The malicious users can create havoc in a CR-MANET by falsifying spectrum sensing information leading to interference with the primary user. The devices in a CR-MANET are mobile, which gives an opportunity for the malicious entity to hide behind the changing neighborhood. We present three solutions to overcome the spectrum sensing data falsification attack and incorrect reporting of signal measurement due to byzantine failures. The first is a multi-fusion based distributed spectrum sensing (MFDSS) using reputation propagation. In the second solution, a continuously evolving virtual neighbor cluster of past neighbor devices aid in validating the input gathered from the current neighboring devices (ReNVaS). Third, a recursive partitioning around medoids based clustering is performed to identify a tightly bound set of valid inputs for decision making (TMC). A unified and non-unified decision making strategy is presented using ReNVaS and TMC. MFDSS performs better in a fast changing network while performance of unified fusion is better in a slow mobility network with respect to primary user spectrum occupancy detection accuracy.
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Title: Reliable and efficient communications in wireless sensor networks
Creator: Abdelhakim, Mai M.
Date: 2014
Collection: Electronic Theses & Dissertations
Description: Wireless sensor network (WSN) is a key technology for a wide range of military and civilian applications. Limited by the energy resources and processing capabilities of the sensor nodes, reliable and efficient communications in wireless sensor networks are challenging, especially when the sensors are deployed in hostile environments. This research aims to improve the reliability and efficiency of time-critical communications in WSNs, under both benign and hostile environments.We start with...
Show moreWireless sensor network (WSN) is a key technology for a wide range of military and civilian applications. Limited by the energy resources and processing capabilities of the sensor nodes, reliable and efficient communications in wireless sensor networks are challenging, especially when the sensors are deployed in hostile environments. This research aims to improve the reliability and efficiency of time-critical communications in WSNs, under both benign and hostile environments.We start with wireless sensor network with mobile access points (SENMA), where the mobile access points traverse the network to collect information from individual sensors. Due to its routing simplicity and energy efficiency, SENMA has attracted lots of attention from the research community. Here, we study reliable distributed detection in SENMA under Byzantine attacks, where some authenticated sensors are compromised to report fictitious information. The q-out-of-m rule is considered. It is popular in distributed detection and can achieve a good trade-off between the miss detection probability and the false alarm rate. However, a major limitation with this rule is that the optimal scheme parameters can only be obtained through exhaustive search. By exploiting the linear relationship between the scheme parameters and the network size, we propose simple but effective sub-optimal linear approaches. Then, for better flexibility and scalability, we derive a near-optimal closed-form solution based on the central limit theorem. It is proved that the false alarm rate of the q-out-of-m scheme diminishes exponentially as the network size increases, even if the percentage of malicious nodes remains fixed. This implies that large-scale sensor networks are more reliable under malicious attacks. To further improve the performance under time-varying attacks, we propose an effective malicious node detection scheme for adaptive data fusion; the proposed scheme is analyzed using the entropy-based trust model, and has shown to be optimal from the information theory point of view.Next, we observe that: while simplifying the routing process, a major limitation with SENMA is that data transmission is limited by the physical speed of the mobile access points (MAs) and the length of their trajectory, resulting in low throughput and large delay. To solve this problem, we propose a novel mobile access coordinated wireless sensor network (MC-WSN) architecture. The proposed MC-WSN can provide reliable and time-sensitive information exchange through hop number control, which is achieved by active network development and topology design. We discuss the optimal topology design for MC-WSN such that the average number of hops between the source and its nearest sink is minimized, and analyze the performance of MC-WSN in terms of throughput, stability, delay, and energy efficiency by exploiting tools in information theory, queuing theory, and radio energy dissipation model. It is shown that MC-WSN achieves much higher throughput and significantly lower delay and energy consumption than that of SENMA.Finally, motivated by the observation that the number of hops in data transmission has a direct impact on the network performance, we introduce the concept of the N-hop networks. Based on the N-hop concept, we propose a unified framework for wireless networks and discuss general network design criteria. The unified framework reflects the convergence of centralized and ad-hoc networks. It includes all exiting network models as special cases, and makes the analytical characterization of the network performance more tractable. Further study on N-hop networks will be conducted in our future research.
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Title: Pulse switching : an ultra-light network paradigm without packet abstraction
Creator: Huo, Qiong
Date: 2013
Collection: Electronic Theses & Dissertations
Description: In this dissertation we develop a novel pulse switching framework for ultra light-weight networking applications involving severely resource-constrained embedded devices. The key idea is to abstract a single pulse, as opposed to multi-bit packets, as the network switching granularity. Pulse switching can be shown to be sufficient for on-off style event monitoring applications for which a monitored parameter can be modeled using just a binary variable. Monitoring such events with conventional...
Show moreIn this dissertation we develop a novel pulse switching framework for ultra light-weight networking applications involving severely resource-constrained embedded devices. The key idea is to abstract a single pulse, as opposed to multi-bit packets, as the network switching granularity. Pulse switching can be shown to be sufficient for on-off style event monitoring applications for which a monitored parameter can be modeled using just a binary variable. Monitoring such events with conventional packet paradigm can be prohibitively inefficient due to the communication, processing, and buffering overheads of the large number of bits within packet data, header, and preambles for synchronization. In the proposed paradigm, an event can be coded as a single pulse, which is then transported multi-hop while preserving sufficient information so that a destination (i.e., sink or actuator nodes) can derive certain spatio-temporal context information about the event in question. The resulting operational lightness, leveraged via zero buffering, no addressing, no packet processing, and an ultra-low communication energy budget makes the framework applicable for embedded devices such as Radio Frequency Identifiers operating with ultra-tight energy budgets, such as from harvested energy.Specific contributions includes: 1) Developing a joint MAC-Routing abstraction for pulse switching, 2) Mapping the proposed pulse switching architecture on Ultra Wideband Band (UWB) impulse radio technology, 3) Developing a hop-angular spatial context abstraction and the related estimation algorithms for event localization, 4) Designing a cellular alternative to the hop-angular abstraction, 5) Designing a peer-to-peer pulse routing protocol, finally 6) System characterization through modeling and large scale simulation.
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Title: Providing source privacy in wireless sensor networks
Creator: Li, Yun
Date: 2010
Collection: Electronic Theses & Dissertations

Title: Preserving source-location privacy in wireless sensor networks
Creator: Lightfoot, Leron J.
Date: 2010
Collection: Electronic Theses & Dissertations
Description: Wireless sensor networks (WSNs) can provide the world with a technology for real-time event monitoring for both military and civilian applications. One of the primary concerns that hinder the successful deployment of wireless sensor networks is source-location privacy. The privacy of the source location is vital and highly jeopardized by the usage of wireless communications.While message content privacy can be ensured through message encryption, it is much more difficult to adequately address...
Show moreWireless sensor networks (WSNs) can provide the world with a technology for real-time event monitoring for both military and civilian applications. One of the primary concerns that hinder the successful deployment of wireless sensor networks is source-location privacy. The privacy of the source location is vital and highly jeopardized by the usage of wireless communications.While message content privacy can be ensured through message encryption, it is much more difficult to adequately address the source-location privacy. For WSNs, source-location privacy service is further complicated by the fact that sensors consist of low-cost and energy efficient radio devices. Therefore, using computationally intensive cryptographic algorithms (such as public-key cryptosystems) and large scale broadcasting-based protocols are not suitable for WSNs.Many protocols have been proposed to provide source-location privacy but most of them are based on public-key cryptosystems, while others are either energy inefficient or have certain security flaws. In this thesis, after analyzing the security weakness of the existing scheme, we propose three routing-based source-location privacy schemes. The first scheme routes each message to a randomly selected intermediate node before it is transmitted to the SINK node. However, this scheme can only provide local source-location privacy. In the second scheme, a network mixing ring (NMR) is proposed to provide network-level source-location privacy. The third scheme achieve network-level source-location privacy through a technique we call the Sink Toroidal Region (STaR) routing. For each of these routing schemes, both security analysis and simulation results show that the proposed schemes are secure and efficient.
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Title: Power management and damage assessment techniques for self-powered sensing based on piezoelectric transduction
Creator: Rhimi, Mohamed
Date: 2013
Collection: Electronic Theses & Dissertations
Description: One major obstacle facing health monitoring systems is the ability to accurately predict remaining life after structural state diagnosis. Today, many remaining life prediction models rely on empirical data which limits their applicability. Moreover, the large scatter in material data, i.e., fatigue, combined with archaic instrumentation has hindered the development and validation of improved prediction models. There is a need for long term continuous monitoring techniques capable of rendering...
Show moreOne major obstacle facing health monitoring systems is the ability to accurately predict remaining life after structural state diagnosis. Today, many remaining life prediction models rely on empirical data which limits their applicability. Moreover, the large scatter in material data, i.e., fatigue, combined with archaic instrumentation has hindered the development and validation of improved prediction models. There is a need for long term continuous monitoring techniques capable of rendering a more precise and reliable stream of data that would enhance the modeling proficiencies and would ultimately help reduce maintenance cost, improve the longevity, and enhance the safety of civil infrastructures.Wireless sensors and sensor networks are emerging as sensing paradigms that the structural engineering field has begun to consider as substitutes for traditional tethered monitoring systems. A major consideration in using a dense sensor array for long term monitoring is the problem of providing power to the sensors. Piezoelectric energy powering has the added advantage to act both as the sensor and as the powering means, thereby reducing the power requirement and cost of the sensor system.Improving the piezoelectric power harvesting from civil structures' vibration while obeying environmental effects (temperature variation) is the first objective of this thesis; the application of a variable preloading condition is used as a solution to modify the cantilever piezoelectric harvester's properties. A generalized model that takes into account more than one vibration-mode shape is derived. Measured acceleration recordings from a concrete bridge deck under ambient loading and recordings from extreme events are used to show the gain in harvested energy when the harvester is in preloaded configuration. The effects of temperature variations on the piezoelectric (PZT) harvested energy from civil structures are also studied. A proposed mechanical tuning, based on the application of an axial load using Shape Memory Alloy to compensate the temperature effect, is presented.The work describing a fully deployed long-term piezoelectric based monitoring system with all needed attributes is the second objective of this work. The calibration and installation of the sensor is addressed. Defining the sensor output from real time loading distribution is shown. The evaluation of a full field data from a limited number of distributed sensor is studied. The damage prediction abilities of the long term self powered continuous monitoring system are evaluated. A slightly modified linear damage accumulation approach is then proposed using the damage index founded on continuum mechanics definition. The derivation of the damage index using sensor's output data is detailed with results from a set of laboratory tests, comparing the damage index prediction output from the sensor and values obtained using the complete time history data. Finally, a projection of the remaining life of tested specimens using reliability analysis was computed and it accuracy was evaluated by completing the test until failure and counting the total real observed cycles, showing very promising results for full field deployment and remaining life prediction with a reasonable accuracy.
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Title: Off-network control processing for scalable routing in very large sensor networks
Creator: Wu, Tao
Date: 2008
Collection: Electronic Theses & Dissertations

Title: Network issues for 3D wireless sensor networks
Creator: Cintrón, Fernando J.
Date: 2013
Collection: Electronic Theses & Dissertations
Description: Wireless sensor networks (WSN) give the opportunity to monitor the environment by performing sensing tasks in places that are difficult to reach or dangerous for humans. Nevertheless, topographical characteristics of such places and the sensor node's limitations introduce new issues in WSN performance. Additionally, in scenarios where sensors are moving or in rugged terrain, there is a high chance for them to be out of communication range, causing network connectivity problems. Hence,...
Show moreWireless sensor networks (WSN) give the opportunity to monitor the environment by performing sensing tasks in places that are difficult to reach or dangerous for humans. Nevertheless, topographical characteristics of such places and the sensor node's limitations introduce new issues in WSN performance. Additionally, in scenarios where sensors are moving or in rugged terrain, there is a high chance for them to be out of communication range, causing network connectivity problems. Hence, solutions have to take into consideration the aspect of the topography consisting of its three dimensional characteristics, namely, type of terrain, terrain unevenness, and obstacles.This dissertation discusses several research topics addressing issues relevant to WSN connectivity and area coverage problems. First, changes in sensor communication range are studied by varying sensors' heights relative to the surface. A novel communication technique that relies on the jumping capabilities of sensors is proposed. While the jumping sensor robots are airborne, the change in elevation enhances their ability for a short time to successfully communicate with other sensors that are out of communication range at the ground level. Field experiments were conducted and results show a considerable improvement in wireless communication ranges.Second, the impact of network connectivity and area coverage in a jumping sensor network is further studied. A Hopping Sensor Network Model is defined to increase sensing area coverage along with the enhancement of network connectivity. A Hopping Sensor Routing Protocol is designed from the model that balances the energy consumption on active jumping sensor nodes. Results from simulations show the increase in area coverage obtained from jumping sensor networks, and the effectiveness of the routing protocol to optimize communication paths while balancing energy depletion in the network.Third, a distributed wireless sensor network organization to establish a functional network, without requiring initial topology information, is presented. Two decentralized algorithms that use the jumping capabilities of sensors are designed for the discovery of isolated sensors. Simulation results show the success of the algorithms to enhance base station reachability. Additionally, cluster to cluster (C-to-C) packet forwarding schemes relying on boundary jumping sensor gateways are defined and analyzed, showing remarkable savings in network energy consumption.Fourth, in order to have a functional network, it is important to address connectivity issues in an application oriented manner. This work presents an efficient node redeployment-decision process to produce a functionally heterogeneous (jumping and non-jumping sensors) WSN with a performance guarantee. Network performance is defined as a network fitness formula considering the network Quality of Connectivity (QoC). Decision making algorithms for node relocation and topology defragmentation are presented, along with a discussion of their performance.Fifth, a multi-step procedure to produce a direction oriented jumping sensor network is presented. A jumping sensor robot approach is introduced for collecting and processing signal strength data into relative geographical orientation information. A directional-orientation decision algorithm is defined to process the orientation information. Furthermore, an error identification and correction procedure is established. This has proven to accurately fix the true orientation of the nodes by using only a pair of location aware beacon nodes.
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Title: Mobility and communication in wireless robot and sensor networks
Creator: Pei, Yuanteng
Date: 2011
Collection: Electronic Theses & Dissertations
Description: Mobility is a primary goal of many wireless communication systems. In recent years, mobile multi-hop wireless networks, such as mobile wireless sensor networks and wireless robot networks, have attracted increased attention and have been extensively studied. However, most current research does not consider the interdependence of communication and mobility and much assume an obstacle-free environment in their problem modeling and solving process.In this dissertation, we discuss several...
Show moreMobility is a primary goal of many wireless communication systems. In recent years, mobile multi-hop wireless networks, such as mobile wireless sensor networks and wireless robot networks, have attracted increased attention and have been extensively studied. However, most current research does not consider the interdependence of communication and mobility and much assume an obstacle-free environment in their problem modeling and solving process.In this dissertation, we discuss several research topics relevant to the above two issues of communication and mobility in wireless robot and sensor networks. First, we present multi-robot real-time exploration, which calls for the joint consideration of mobility and communication: it requires video and audio streams of a newly explored area be transmitted to the base station in a timely fashion as robots explore the area. Simulations show that our mobility model has achieved both improved communication quality and enhanced exploration efficiency.Second, we further investigate the above problem with two critical and real-world network conditions: (1) heterogeneous transmission ranges and link capacities, and (2) the impact of interference. The conditions increase the model complexity but significantly influence the actual available bandwidth and the required node size in placement. We jointly consider the relay placement and routing with these two critical conditions.Third, we introduce an online relay deployment paradigm to support remote sensing and control when mobile nodes migrate farther from the base station in a cost-effective system of mobile robots, static sensors and relays. A novel multi-robot real-time search method called STAtic Relay aided Search (STARS) is presented to allow robots to search in a known environment. Its solution is based on our near-optimal solution to a new variation of the multi-traveling salesman problem: precedence constrained two traveling salesman (PC2TSP).Fourth, we propose a heterogenous multi-robot exploration strategy with online relay deployment for an unknown environment called Bandwidth aware Exploration with a Steiner Traveler (BEST). In BEST, a relay-deployment node (RDN) tracks the FNs movement and places relays when necessary to support the video/audio streams aggregation to the base station. This problem inherits characteristics of both the Steiner minimum tree and traveling salesman problems. Extensive simulations show that BEST further enhances the exploration efficiency.While the first four topics deal with communication and mobility issues in powerful but expensive robotic systems, the fifth topic focuses on a special type of low cost, limited capability mobile sensors called hopping sensors, whose unique method of movement makes them suitable for rugged terrains. We present (1) a distributed message forwarding model called Binary Splitting Message Forwarding (BSMF) and (2) a grid based movement model unique to these hopping sensors. Simulation shows that our scheme significantly reduces the communication overhead and achieves relatively constant total energy consumption with varying amount of obstructions.Finally, we discuss the future work directions of this research work. We believe that a heterogeneous mobile platform to support real-time stream transmission by mobile robots, static sensor and communication devices, have great potential in various civilian and military applications, where the communication quality of service is critically important, as well as the mobility efficiency.
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Title: Improving spectrum efficiency in heterogeneous wireless networks
Creator: Liu, Chin-Jung
Date: 2018
Collection: Electronic Theses & Dissertations
Description: Over the past decades, the bandwidth-intensive applications that are previously confined to wired networks are now migrating to wireless networks. This trend has brought unprecedented high demand for wireless bandwidth. The wireless traffic is destined to dominate the Internet traffic in the future, but many of the popular wireless spectrum bands, especially the cellular and ISM bands, are already congested. On the other hand, some other wireless technologies, such as TV bands, often do not...
Show moreOver the past decades, the bandwidth-intensive applications that are previously confined to wired networks are now migrating to wireless networks. This trend has brought unprecedented high demand for wireless bandwidth. The wireless traffic is destined to dominate the Internet traffic in the future, but many of the popular wireless spectrum bands, especially the cellular and ISM bands, are already congested. On the other hand, some other wireless technologies, such as TV bands, often do not fully utilize their spectrum. However, the spectrum allocation is tightly regulated by the authority and adjusting the allocation is extremely difficult. The uneven utilization and the rigid regulation have led to the proposal of heterogeneous wireless networks, including cognitive radio networks (CRN) and heterogeneous cellular networks (HetNet). The CRNs that usually operate on different technologies from the spectrum owner attempt to reuse the idle spectrum (i.e., white space) from the owner, while HetNets attempt to improve spectrum utilization by smallcells. This dissertation addresses some of the challenging problems in these heterogeneous wireless networks.In CRNs, the secondary users (SU) are allowed to access the white spaces opportunistically as long as the SUs do not interfere with the primary users (PU, i.e., the spectrum owner). The CRN provides a promising means to improve spectral efficiency, which also introduces a set of new research challenges. We identify and discuss two problems in CRNs, namely non-contiguous control channel establishment and k-protected routing protocol design. The first problem deals with the need from SUs for a channel to transfer control information. Most existing approaches are channel-hopping (CH) based, which is inapplicable to NC-OFDM. We propose an efficient method for guaranteed NC-OFDM-based control channel establishment by utilizing short pulses on OFDM subcarriers. The results show that the time needed for establishing control channel is lower than that of CH-based approaches. The second problem deals with the interruption to a routing path in a CRN when a PU becomes active again. Existing reactive approaches that try to seek for an alternative route after PU returns suffer from potential long delay and possible interruption if an alternative cannot be found. We propose a k-protected routing protocol that builds routing paths with preassigned backups that are guaranteed to sustain from k returning PUs without being interrupted. Our result shows that the k-protected routing paths are never interrupted even when k PUs return, and have significantly shorter backup activation delays.HetNets formed by smallcells with different sizes of coverage and macrocells have been proposed to satisfy increased bandwidth demand with the limited and crowded wireless spectrum. Since the smallcells and macrocells operate on the same frequency, interference becomes a critical issue. Detecting and mitigating interference are two of the challenges introduced by HetNets. We first study the interference identification problem. Existing interference identification approaches often regard more cells as interferers than necessary. We propose to identify interference by analyzing the received patterns observed by the mobile stations. The result shows that our approach identifies all true interferers and excludes most non-interfering cells. The second research problem in HetNets is to provide effective solutions to mitigate the interference. The interference mitigation approaches in the literature mainly try to avoid interference, such as resource isolation that leads to significantly fewer resources, or power control that sacrifices signal quality and coverage. Instead of conservatively avoiding interference, we propose to mitigate the interference by precanceling the interfering signals from known interferers. With precancellation, the same set of resources can be shared between cells and thus throughput is improved.This dissertation addresses several challenges in heterogeneous wireless networks, including CRNs and HetNets. The proposed non-contiguous control channel protocol and k-protected routing protocol for CRNs can significantly improve the feasibility of CRNs in future wireless network applications. The proposed interference identification and interference precancellation approaches can effectively mitigate the interference and improve the throughput and spectrum utilization in HetNets. This dissertation aims at breaking the barriers for supporting heterogeneous wireless networks to improve the utilization of the precious and limited wireless spectrum.
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Title: Implementation of a high throughput low power MAC protocol in wireless sensor networks
Creator: Liu, Chin-Jung
Date: 2011
Collection: Electronic Theses & Dissertations
Description: This thesis presents the design, implementation, and evaluation of TATD-MAC, a TDMA-based low duty cycle synchronous MAC protocol that improves throughput by increasing channel uti- lization with a traffic-adaptive time slot scheduling method. Conventional time division multiple access (TDMA) introduces significant end-to-end packet delivery delay and its throughput is lim- ited. TATD-MAC achieves higher throughput by improving TDMA with a novel traffic-adaptive mechanism that assigns time...
Show moreThis thesis presents the design, implementation, and evaluation of TATD-MAC, a TDMA-based low duty cycle synchronous MAC protocol that improves throughput by increasing channel uti- lization with a traffic-adaptive time slot scheduling method. Conventional time division multiple access (TDMA) introduces significant end-to-end packet delivery delay and its throughput is lim- ited. TATD-MAC achieves higher throughput by improving TDMA with a novel traffic-adaptive mechanism that assigns time slots only to nodes that are expecting traffic. Our traffic-adaptive mechanism is a two-phase design, which decomposes the DATA period into traffic notification part and data transmission scheduling part. The two-phase design enables TATD-MAC to optimize the control packets and improve their energy efficiencies according to the characteristics of each phase. The source nodes inform all nodes on the routing path that these sources have outgoing traffic by transmitting traffic notification packets in a "pulse" fashion. With traffic notification packets, ev- ery node on the routing path claims time slots in data transmission part. Therefore, TATD-MAC is able to forward a packet over multiple hops in a single cycle and thus reduce the end-to-end delay. The data transmission scheduling mechanism only assigns time slots to nodes with traf- fic through an ordered schedule negotiation scheme. This innovative traffic-adaptive scheduling mechanism assigns time slots based on traffic and totally eliminates the idle listening slots on nodes with no traffic. Moreover, if any other nodes need more time slots, they are able to claim them, which further improves channel utilization and achievable throughput. We implemented a TATD-MAC prototype on Tmote-Sky running TinyOS 2.1.0. Performance evaluation shows that TATD-MAC significantly improves throughput compared to conventional TDMA and achieves the same throughput as TDMA with slot stealing while having 70% less power consumption.
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Title: Gliding robotic fish : design, collaborative estimation, and application to underwater sensing
Creator: Ennasr, Osama Nasr
Date: 2020
Collection: Electronic Theses & Dissertations
Description: Autonomous underwater robots have received significant attention over the past two decades due to the increasing demand for environmental sustainability. Recently, gliding robotic fish has emerged as a promising mobile sensing platform in versatile aquatic environments. Such robots, inspired by underwater gliders and robotic fish, combine buoyancy-driven gliding and fin-actuated swimming to realize both energy-efficient locomotion and high maneuverability. In this dissertation, we first...
Show moreAutonomous underwater robots have received significant attention over the past two decades due to the increasing demand for environmental sustainability. Recently, gliding robotic fish has emerged as a promising mobile sensing platform in versatile aquatic environments. Such robots, inspired by underwater gliders and robotic fish, combine buoyancy-driven gliding and fin-actuated swimming to realize both energy-efficient locomotion and high maneuverability. In this dissertation, we first discuss the design improvements for the second-generation gliding robotic fish "Grace 2". These improvements have transformed the robots to underwater sensing platforms that can be modified to fit the requirements of a specific application with relative ease.We focus on the application of detecting and tracking live fish underwater, which is an important part of fishery research, as it helps scientists understands habitat use, migratory patterns, and spawning behavior of fishes. The gliding robotic fish has demonstrated its ability to detect special acoustic signals emulating tagged fish through a series of trials in Higgins Lake, Michigan. These tests have also validated a gliding-based strategy for navigating to a GPS waypoint, and offered insight into the limitations of the current design. Additional improvements are proposed to allow these robots to glide at larger depths and perform more interesting working patterns underwater.Motivated by the problem of tracking real fish, we consider the case where multiple robots localize and track a moving target without the need for a centralized node. We present theoretical treatment on how a network of robots can infer the location of an emitter (or target), and then track it, through a time-difference-of-arrival (TDOA) localization scheme in a fully distributed manner. In particular, we utilize a networked extended Kalman filter to estimate the target's location in a distributed manner, and establish that successful localization can be achieved under fixed and time-varying undirected communication topologies if every agent is part of a network with a minimum of 4 connected, non-coplanar agents. We further propose a movement control strategy based on the norm of the estimation covariance matrices, with a tuning parameter to balance the trade-off between estimation performance and the total distance traveled by the robots.Finally, motivated by the distributed localization problem, we investigate a more general problem of distributed estimation by a network of sensors. Specifically, we consider the class of consensus-based distributed linear filters (CBDLF) where each sensor updates its estimate in two steps: a consensus step dictated by a weighted and directed communication graph, followed by a local Luenberger filtering step. We show that the sub-optimal filtering gains that minimize an upper bound of a quadratic filtering cost are related to the convergence of a set of coupled Riccati equations. Then we show that the convergence of these coupled Riccati equations depends on the notion of squared detectability for the networked system, and proceed to provide necessary conditions that link the convergence of the coupled Riccati equations to the network topology and consensus weights of the communication graph.
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Title: Exploiting node mobility for energy optimization in wireless sensor networks
Creator: El-Moukaddem, Fatme Mohammad
Date: 2012
Collection: Electronic Theses & Dissertations
Description: Wireless Sensor Networks (WSNs) have become increasingly available for data-intensive applications such as micro-climate monitoring, precision agriculture, and audio/video surveillance. A key challenge faced by data-intensive WSNs is to transmit the sheer amount of data generated within an application's lifetime to the base station despite the fact that sensor nodes have limited power supplies such as batteries or small solar panels. The availability of numerous low-cost robotic units (e.g....
Show moreWireless Sensor Networks (WSNs) have become increasingly available for data-intensive applications such as micro-climate monitoring, precision agriculture, and audio/video surveillance. A key challenge faced by data-intensive WSNs is to transmit the sheer amount of data generated within an application's lifetime to the base station despite the fact that sensor nodes have limited power supplies such as batteries or small solar panels. The availability of numerous low-cost robotic units (e.g. Robomote and Khepera) has made it possible to construct sensor networks consisting of mobile sensor nodes. It has been shown that the controlled mobility offered by mobile sensors can be exploited to improve the energy efficiency of a network.In this thesis, we propose schemes that use mobile sensor nodes to reduce the energy consumption of data-intensive WSNs. Our approaches differ from previous work in two main aspects. First, our approaches do not require complex motion planning of mobile nodes, and hence can be implemented on a number of low-cost mobile sensor platforms. Second, we integrate the energy consumption due to both mobility and wireless communications into a holistic optimization framework.We consider three problems arising from the limited energy in the sensor nodes. In the first problem, the network consists of mostly static nodes and contains only a few mobile nodes. In the second and third problems, we assume essentially that all nodes in the WSN are mobile. We first study a new problem called max-data mobile relay configuration (MMRC) that finds the positions of a set of mobile sensors, referred to as relays, that maximize the total amount of data gathered by the network during its lifetime. We show that the MMRC problem is surprisingly complex even for a trivial network topology due to the joint consideration of the energy consumption of both wireless communication and mechanical locomotion. We present optimal MMRC algorithms and practical distributed implementations for several important network topologies and applications. Second, we consider the problem of minimizing the total energy consumption of a network. We design an iterative algorithm that improves a given configuration by relocating nodes to new positions. We show that this algorithm converges to the optimal configuration for the given transmission routes. Moreover, we propose an efficient distributed implementation that does not require explicit synchronization. Finally, we consider the problem of maximizing the lifetime of the network. We propose an approach that exploits the mobility of the nodes to balance the energy consumption throughout the network. We develop efficient algorithms for single and multiple round approaches. For all three problems, we evaluate the efficiency of our algorithms through simulations. Our simulation results based on realistic energy models obtained from existing mobile and static sensor platforms show that our approaches significantly improve the network's performance and outperform existing approaches.
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Title: Environmental acoustics as an ecological variable to understand the dynamics of ecosystems
Creator: Joo, Wooyeong
Date: 2009
Collection: Electronic Theses & Dissertations

Title: Development of small biomimetic robotic fish with onboard fine-grained localization
Creator: Shatara, Stephan W.
Date: 2008
Collection: Electronic Theses & Dissertations

Title: Design and implementation of integrated self-powered sensors, circuits and systems
Creator: Huang, Chenling
Date: 2011
Collection: Electronic Theses & Dissertations
Description: Wireless sensor systems have been widely used for both industrial and civil applications. With the development of circuit design and fabrication technique, sensor nodes now can be implemented with small scale at low cost, which is promising for ubiquitous sensing. However, with more functions integrated, the conflict between power consumption and expected lifetime became critical. Sensor nodes powered with batteries are generally compromised by extra physical size and periodic battery...
Show moreWireless sensor systems have been widely used for both industrial and civil applications. With the development of circuit design and fabrication technique, sensor nodes now can be implemented with small scale at low cost, which is promising for ubiquitous sensing. However, with more functions integrated, the conflict between power consumption and expected lifetime became critical. Sensor nodes powered with batteries are generally compromised by extra physical size and periodic battery replacement. Therefore, energy harvesting techniques are intensively involved in sensor design where environmental signal acts as auxiliary energy source.A typical energy harvesting sensor consists of four parts: energy harvester, energy storage, power management and sensor subsystem. Energy harvester scavenges power from environmental signal which is then transferred into energy storage. Since the output power is usually not in appropriate form, power management is used to provide a usable supply voltage/current for sensor subsystem. The limitation of energy harvesting sensor is determined by the power consumption of sensor subsystem, the efficiency of energy conversion and the available energy level from environment.In this dissertation, a novel solution referred as "self-powered sensor" is proposed to extend the limitation of energy harvesting sensor. The proposed sensor can directly harvest energy from input signal being sensed. Therefore the usage of energy storage and power management is eliminated, which achieves higher energy efficiency.To demonstrate proposed solution, the system and circuit design of a self-powered sensor are presented for long-term ambient vibration monitoring. Constrained by its application, the sensor can only scavenge energy from input strain signal itself, in which scenario all existing energy harvesting techniques fail. The greatest design challenge is to achieve both ultra-low power computation and non-volatile storage. In this dissertation, a novel technique based on floating-gate transistor is presented. By exploiting controllable hot electron injection procedure, specific computation can be performed according to the characteristic of input signal. In addition, floating-gates can also retain computation results with no power consumption.For autonomous sensing, a hybrid energy harvesting topology is proposed on system level. The sensor is designed with two different operation modes. In self-powered sensing mode, it can perform continuous monitoring, computation and data storage which is powered by input strain signal. In data interrogating mode, additional functions such as data sampling and wireless communication can be enabled once a certain reading device is provided.The dissertation is organized as follows. In chapter 1, the history of wireless sensor system is reviewed. The motivation of self-powered sensor and the contributions of this dissertation are presented. Existing energy harvesting techniques are evaluated in chapter 2. In chapter 3, the case of long-term ambient vibration monitoring is studied and the hybrid energy harvesting topology is proposed for self-powered sensor system. In chapter 4, the principle of ultra-low power computation and non-volatile storage is explored based on controllable injection procedure on floating-gate transistor. To verified proposed solution, a sensor prototype was fabricated in 0.5-um standard CMOS process. The details of circuit design and evaluation are presented in chapter 5, including analog signal processor, analog-to-digital converter, radio frequency front-end, digital baseband, etc. Chapter 6 shows an extension of ultrasonic powering and communication system based on preliminary work and chapter 7 draws final remarks.
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Title: Design and deployment of low-cost wireless sensor networks for real-time event detection and monitoring
Creator: Phillips, Dennis Edward
Date: 2018
Collection: Electronic Theses & Dissertations
Description: As sensor network technologies become more mature, they are increasingly being applied to a wide variety of environmental monitoring applications, ranging from agricultural sensing to habitat monitoring, oceanic and volcanic monitoring. In this dissertation two wireless sensor networks (WSNs) are presented. One for monitoring residential power usage and another for producing an image of a volcano's internal structure.The two WSNs presented address several common challenges facing modern...
Show moreAs sensor network technologies become more mature, they are increasingly being applied to a wide variety of environmental monitoring applications, ranging from agricultural sensing to habitat monitoring, oceanic and volcanic monitoring. In this dissertation two wireless sensor networks (WSNs) are presented. One for monitoring residential power usage and another for producing an image of a volcano's internal structure.The two WSNs presented address several common challenges facing modern sensor networks. The first is in-network processing and assigning the processing tasks across a heterogeneous network architecture. By efficiently utilizing in-network processing power consumption can be reduced and operational lifetime of the network can be extended. As nodes are embedded into various environments sensing accuracy is intrinsically affected by physical noise. The second challenge relates to how to deal with this noise in a way which increases sensing accuracy. The third challenge is ease of deployment. As WSNs become more common place they will be installed by non-experts.As a key technology of home area networks in smart grids, fine-grained power usage monitoring may help conserve electricity. Smart homes outfitted with network connected appliances will provide this capability in the future. Until smart appliances have wide adaption there is a serious gap in capabilities. To fill this gap an easy to deploy monitoring system is needed. Several existing systems achieve the goal of fine-grained power monitoring by exploiting appliances' power usage signatures utilizing labor-intensive in situ training processes. Recent work shows that autonomous power usage monitoring can be achieved by supplementing a smart meter with distributed sensors that detect the working states of appliances. However, sensors must be carefully installed for each appliance, resulting in high installation cost. Supero is the first ad hoc sensor system that can monitor appliance power usage without supervised training. By exploiting multi-sensor fusion and unsupervised machine learning algorithms, Supero can classify the appliance events of interest and autonomously associate measured power usage with the respective appliances. Extensive evaluation in five real homes shows that Supero can estimate the energy consumption with errors less than 7.5%. Moreover, non-professional users can quickly deploy Supero with considerable flexibility.There are a number of active volcanos around the world with large population areas located nearby. An eruption poses a significant threat to the adjacent population. During times of increased activity being able to obtain a real-time images of the interior would allow seismologists to better understand volcanic dynamics. Volcano tomography can provide this valuable information concerning the internal structure of a volcano. The second sensor network presented in this dissertation is a seismic monitoring sensor network featuring in-network processing of the seismic signals with the capability to perform volcano tomography in real-time. The design challenges, analysis of processing/network processing times in the information processing pipeline, the system designed to meet these challenges and the results from deploying a prototype network on two volcanoes in Ecuador and Chile are presented. The study shows that it is possible to achieve in-network seismic event detection and real-time tomography using a sensor network that is 2 orders of magnitude less expensive than traditional seismic equipment.
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