With the emergence of the Internet of things (IoT) networks, the replacement of batteries for IoT devices became challenging. In particular, the battery replacement is more expensive and cumbersome for scenarios where there are many IoT devices; or where the IoT devices are in unreachable locations; or when they have to be replaced often. Some IoT devices might be lost or forgotten, and there is a risk of hazardous chemicals leakage and e-waste in large scale in nature. Radio frequency (RF) wireless power transfer (WPT) is an alternative technology for powering those devices. It has been shown that only less than one millionth of the transmitted energy is absorbed by the receivers, the rest is absorbed by the objects in the environment. We can utilize the existing infrastructure for wireless communications such as base stations (BS) to charge IoT devices. The present work is devoted to analyze the feasibility and limitations of the battery-less operation of IoT devices with RF WPT technology and energy harvesting from existing infrastructure for wireless communications. We study the indoor and outdoor scenarios for powering of IoT devices. In the first scenario, we consider an outdoor environment where an IoT device periodically harvests energy from an existing BS and transmits a data packet related to the sensor measurement under shadow fading channel conditions. We analyze the limits (e.g., coverage range) of energy harvesting from a BS for powering IoT devices. We characterize the "epsilon-coverage range, where" is the probability of the coverage. Our analysis shows a tradeoff between the coverage range and the rate of sensor measurements, where the maximal "epsilon-coverage range is achieved as the sensor measurement rate approaches zero. We demonstrate that the summation of the sleep power consumption and the harvesting sensitivity power of an IoT device limits the maximal "epsilon-coverage range. Beyond that range, the IoT device cannot harvest enough energy to operate. The desired rate of the sensor measurements also significantly impacts the "epsilon-coverage range. We also compare the operational domain in terms of the range and measurement rate for the WPT and battery-powered technologies. In the second scenario, we consider the remote powering of IoT devices inside an aircraft. Sensors currently deployed on board have wired connectivity, which increases weight and maintenance costs for aircraft. Removing cables for wireless communications of sensors on board alleviates the cost, however, the powering of sensors becomes a challenge inside aircraft. We assume that the IoT devices have fixed and known locations inside an aircraft. The design problem is to minimize the number of WPT transmitters given constraints based on the cabin geometry and duty cycle of the IoT devices. We formulate a robust optimization problem to address the WPT system design under channel uncertainties. We also derive an equivalent integer linear programming and solve that for an optimal deployment to satisfy the duty cycle requirements of the cabin sensors. / <p>QC 20220223</p><p></p>

Wireless sensor networks are composed of large numbers-up to thousands-of tiny radio-equipped sensors. Every sensor has a small microprocessor with enough power to allow the sensors to autonomously form networks through which sensor information is gathered. Wireless sensor networks makes it possible to monitor places like nuclear disaster areas or volcano craters without requiring humans to be immediately present. Many wireless sensor network applications cannot be performed in isolation; the sensor network must somehow be connected to monitoring and controlling entities. This thesis investigates a novel approach for connecting sensor networks to existing networks: by using the TCP/IP protocol suite in the sensor network, the sensors can be directly connected to an outside network without the need for special proxy servers or protocol converters. Bringing TCP/IP to wireless sensor networks is a challenging task, however. First, because of their limited physical size and low cost, sensors are severely constrained in terms of memory and processing power. Traditionally, these constraints have been considered too limiting for a sensor to be able to use the TCP/IP protocols. In this thesis, I show that even tiny sensors can communicate using TCP/IP. Second, the harsh communication conditions make TCP/IP perform poorly in terms of both throughput and energy efficiency. With this thesis, I suggest a number of optimizations that are intended to increase the performance of TCP/IP for sensor networks. The results of the work presented in this thesis has had a significant impact on the embedded TCP/IP networking community. The software developed as part of the thesis has become widely known in the community. The software is mentioned in books on embedded systems and networking, is used in academic courses on embedded systems, is the focus of articles in professional magazines, is incorporated in embedded operating systems, and is used in a large number of embedded devices. / Contiki / uIP

Cette thèse a pour objectif de développer des techniques permettant d'améliorer l'efficacité énergétique des réseaux de capteurs destinés à la surveillance d'une chaîne de froid. La première approche développée dans cette thèse concerne la phase de transport des produits alimentaires. Les protocoles proposés VBS, WaS et eVBS s'adressent à la problématique posée par l'absence de station de base permanente au sein du petit réseau déployé dans un camion où les nœuds sont en visibilité directe. Ces méthodes ont le triple avantage de présenter un faible overhead, d'accroître l'ergonomie de l'application et l'intérêt économique du réseau. Dans l'état de l'art, il n'existe pas de déploiement de très grands réseaux de capteurs sans fil destinés à la surveillance d'une chaîne de froid. Le cœur de cette thèse se positionne ainsi autour de la problématique du passage à l'échelle, en proposant plusieurs approches permettant d'améliorer l'efficacité énergétique du réseau. Ainsi des optimisations du routage et des techniques de formation de clusters multi-sauts sont proposées grâce à quelques idées originales d'utilisation de l'indicateur de la qualité de lien. Le protocole L2RP de routage par répartition de charge, le mécanisme SNCR de réduction des clusters singletons ainsi que le protocole LQI-DCP d'optimisation du positionnement des chefs de clusters sont des contributions de cette thèse exploitant le LQI afin d'accroître l'efficacité énergétique du réseau. De plus, nous avons montré que l'heuristique MaxMin de formation de clusters multi-sauts n'est pas compatible avec la topologie de déploiement en grille qui est la plus fréquente dans les architectures de réseaux de capteurs. / Wireless Sensor Networks (WSN) are used today in many applications that differ in their own objectives and specific constraints. However the common challenge in designing WSN applications comes from the specific constraints of micro-sensors because of their limited physical resources such as limited battery lifetime, weak computational capability and small memory capacity. This thesis aims to develop techniques to improve the energy efficiency of wireless sensor networks intended to a cold chain monitoring application. In such area, existing solutions consist of walled temperature recorders in warehouses and transport vehicles, which essentially control the room storage temperature which is not necessarily the product one. By integrating wireless micro-sensor devices with pallets and trays, one allows full real-time tracking of the cold chain originating from factories to the shelves of retailers. The first approach developed in this thesis concerns the phase of transporting food. The proposed VBS, WaS and eVBS protocols address the main issue resulting from the absence of a permanent base station in the small network deployed in a truck where nodes are generally in the same transmission range. These methods have the triple advantages of having a low overhead, increasing the ergonomics of the application and enhancing the economic interest of the network. In the state of art, there is no very large scale deployment of WSN for a cold chain monitoring system. Thus, the core of this thesis addresses the scalability issues by offering several ways to improve overall energy efficiency of the network. So, routing techniques improvement and efficient multi-hop clustering protocols are proposed through some original ideas using the Link Quality Indicator (LQI) provided by the MAC sublayer. The LQI is defined in the IEEE 802.15.4 standard in which its context of use is not specified. The link reliability based routing protocol (L2RP) which load balances the traffic between nodes, the single-node cluster reduction mechanism (SNCR) and the LQI-DCP multi-hop clusters formation protocol which improves clusterhead locations are some of contributions of this thesis which exploit the LQI to, significantly, increase the WSN efficiency. We also show that the MaxMin d-cluster formation heuristic does not support the grid deployment topology which is the more often used in WSN architectures.

Indiana University-Purdue University Indianapolis (IUPUI) / This thesis discusses about developing a routing protocol of mobile ad hoc networks in a bio inspired manner. Algorithms inspired by collective behaviour of social insect colonies, bird flocking, honey bee dancing, etc., promises to be capable of catering to the challenges faced by tiny wireless sensor networks. Challenges include but are not limited to low bandwidth, low memory, limited battery life, etc. This thesis proposes an energy efficient multi-path routing algorithm based on foraging nature of ant colonies and considers many other meta-heuristic factors to provide good robust paths from source node to destination node in a hope to overcome the challenges posed by resource constrained sensors. / 2020-12-31

The operational life of wireless sensor network based distributed sensing systems is limited by the energy provided by a portable battery pack. Owing to the inherently resource constrained nature of wireless sensor networks and nodes, a major research thrust in this field is the search for energy-aware methods of operation. Communication is among the most energy-intensive operations on a wireless device. It is therefore, the focus of our efforts to develop an energy-aware method of communication and to introduce a degree of reconfigurability to ensure autonomous operation of such devices. Given this background, three research tasks have been identified and investigated during the course of this research. 1) Devising an energy-efficient method of communication in a framework of reconfigurable operation: The dependence of the energy consumed during communication on the number of bits transmitted (and received) was identified from prior research work. A novel method of data compression was designed to exploit this dependence. This method uses the time-limited, orthonormal Walsh functions as basis functions for representing signals. The L2 norm of this representation is utilized to further compress the signals. From Parseval’s relation, the square of the L2 norm represents the energy content of a signal. The application of this theorem to our research makes it possible to use the L2 norm as a control knob. The operation of this control knob makes it possible to optimize the number of terms required to represent signals. The time-limited nature of the Walsh functions was leveraged to inject dynamic behaviour into our coding method. This time-limited nature allows decomposition of finite time-segments, without attendant limitations like loss of resolution that are inherent to derived, discrete transforms like the discrete Fourier transform or the discrete time Fourier transform. This decomposition over successive, finite time-segments, coupled with innovative operation of the previously mentioned control knob on every segment, gives us a dynamic scaling technique. The amount of data to be transmitted is in turn based on the magnitude of the coefficients of decomposition of each time-segment, leading to the realization of a variable word length coding method. This dynamic coding method can identify evolving changes or events in the quantity being sensed. The coefficients of decomposition represent features present in successive time-segments of signals and therefore enable identification of evolving events. The ability to identify events as they occur enables the algorithm to react to events as they evolve in the system. In other words the data transmission and the associated energy consumption are imparted a reconfigurable, event-driven nature by implementation of the coding algorithm. Performance evaluation of this method via simulations on machine generated (bearing vibration) and biometric (electro-cardio gram) signals shows it be a viable method for energy-aware communication. 2) Developing a framework for reconfigurable triggering: A framework for completely autonomous triggering of the coding method has been developed. This is achieved by estimating correlations of the signal with the representative Walsh functions. The correlation coefficient of a signal segment with a Walsh function gives a picture of the amount of energy localized by the function. This information is used to autonomously tune the abovementioned control knob or, in more proper terms, the degree of thresholding used in compression. Evaluation of this framework on bearing vibration and electro-cardio gram signals has shown results consistent with those of previous simulations. 3) Devising a computationally compact method of feature classification: A method of investigating time series measurements of dynamic systems in order to classify features buried in the signal measurements was investigated. The approach involves discretizing time-series measurements into strings of pre-defined symbols. These strings are transforms of the original time-series measurements and are a representation of the system dynamics. A method of statistically analyzing the symbol strings is presented and its efficacy is studied through representative simulations and experimental investigation of vibration signals recorded from a rolling bearing element. The method is computationally compact because it obviates the need for local signal processing tasks like denoising, detrending and amplification. Results indicate that the method can effectively classify deteriorating machine health, changing operating conditions and evolving defects. In addition to these major foci, another research task was the design and implementation of a wireless network testbed. This testbed consists of a network of netbooks, connected together wirelessly and was utilized for experimental verification of the variable word length coding method.

Indiana University-Purdue University Indianapolis (IUPUI) / Today, Wireless Sensor Networks (WSNs) are forming an exciting new area to have dramatic impacts on science and engineering innovations. New WSN-based technologies, such as body sensor networks in medical and health care and environmental monitoring sensor networks, are emerging. Sensor networks are quickly becoming a flexible, inexpensive, and reliable platform to provide solutions for a wide variety of applications in real-world settings. The increase in the proliferation of sensor networks has paralleled the use of more heterogeneous systems in deployment. In this thesis, our work attempts to develop a new network management and data collection framework for heterogeneous wireless sensor networks called as Heterogeneous Wireless Sensor Networks Management System (H-WSNMS), which enables to manage and operate various sensor network systems with unified control and management services and interface. The H-WSNMS framework aims to provide a scheme to manage, query, and interact with sensor network systems. By introducing the concept of Virtual Command Set (VCS), a series of unified application interfaces and Metadata (XML files) across multiple WSNs are designed and implement the scalability and flexibility of the management functions for heterogeneous wireless sensor networks, which is demonstrated though through a series of web-based WSN management Applications such as Monitoring, Configuration, Reprogram, Data Collection and so on. The tests and application trials confirm the feasibility of our approach but also still reveal a number of challenges to be taken into account when deploying wireless sensor and actuator networks at industrial sites, which will be considered by our future research work.

No description available.

Monitoring the structural health of civil infrastructures with wireless sensor networks aids in detecting failures early, but faces power challenges in ensuring reasonable network lifetimes. Recharging select nodes with Unmanned Aerial Vehicles (UAVs) provides a solution that currently can recharge a single node; however, questions arise on the effectiveness of a limited recharging system, the appropriate node to recharge, and the best sink selection algorithm for improving network lifetime given a limited recharging system. This paper simulates such a network in order to answer those questions. This thesis first determines whether or not recharging with a UAV is an effective method of delivering limited power to the network. It then determines the best way to deliver that power. Finally, this thesis explores five different sink positioning algorithms to find which optimize the network lifetime by load-balancing the energy in the network, all in combination with the added capability of a UAV.

Wireless sensor networks have become a rapidly growing research field in recent years. They are envisioned to have a wide range of applications in military, environmental and many other fields. We examine the performance of wireless sensor network applications to aeronautical telemetry. To date, test ranges have relied on a single telemetry ground station for the reception of packets from all air borne transmitters. We researched an alternate means of achieving this same goal with fewer resources. It is a well known fact that communication power and bandwidth are the most expensive commodities in wireless communications. The telemetry world is ever in need of ways and means to reduce power requirements of its networks while maximizing the use of available bandwidth. In our alternate method, packets will be reliably transported to a centrally located monitoring station in a series of hops. We will effectively reduce the power requirements of the network by minimizing the distance coverage of the sensor nodes. We will also explore different network topologies with a view to maximizing the use of available bandwidth. The alternate method will present a less expensive way to implement telemetry networks. Currently, telemetry networks make use of a single, huge and expensive base station receiving packets from all airplanes in test. Affordable sensor nodes placed strategically on the range and configured properly will achieve the same goal in a cost effective, power saving and bandwidth considerate manner.

Wireless sensor network (WSN) nodes communicate securely using pre-installed cryptographic keys. Although key pre-installation makes nodes less expensive, the technical process of installing keys prevents average users from deploying and controlling their own WSNs. Wireless pairing enables users to set up WSNs without pre-installing keys, but current pairing techniques introduce numerous concerns regarding security, hardware expense, and usability. This thesis introduces dynamic Near Field Communication (NFC) pairing, a new pairing technique designed for WSNs. This pairing overcomes the limitations of both key pre-installation and current pairing techniques. Dynamic NFC pairing is as secure as using pre-installed keys, requires only inexpensive NFC hardware, and is easy to use since the user simply holds nodes close together to add them to a network. A sample application shows the power of dynamic NFC pairing. The user adds sensors and actuators to a WSN by holding each node close to a central node or network coordinator. Data readings stream instantly from each sensor to a web page where the user may view data as well as click buttons to cause events to occur on the actuators. This happens quickly and securely without exposing the user to the complexity of cryptographic keys.