Master of Science / Department of Electrical and Computer Engineering / William B. Kuhn and Balasubramaniam Natarajan / This thesis presents an energy harvesting wireless sensor network (EHWSN) architecture customized for use within a space suit. The contribution of this research spans both physical (PHY) layer energy harvesting transceiver design and appropriate medium access control (MAC) layer solutions. The EHWSN architecture consists of a star topology with two types of transceiver nodes: a powered Gateway Radio (GR) node and multiple energy harvesting (EH) Bio-Sensor Radio (BSR) nodes. A GR node works as a central controller to receive data from BSR nodes and manages the EHWSN via command packets; low power BSR nodes work to obtain biological signals, packetize the data and transmit it to the GR node. To demonstrate the feasibility of an EHWSN at the PHY layer, a representative BSR node is designed and implemented. The BSR node is powered by a thermal energy harvesting system (TEHS) which exploits the difference between the temperatures of a space suit's cooling garment and the astronaut's body. It is shown that through appropriate control of the duty-cycle in transmission and receiving modes, it is possible for the transceiver to operate with less than 1mW power generated by the TEHS. A super capacitor, energy storage of TEHS, acts as an energy buffer between TEHS and power consuming units (processing units and transceiver radio). The super capacitor charges when a BSR node is in sleep mode and discharges when the node is active. The node switches from sleep mode to active mode whenever the super capacitor is fully charged. A voltage level monitor detects the system's energy level by measuring voltage across the super capacitor. Since the power generated by the TEHS is extremely low(less than 1mW) and a BSR node consumes relatively high power (approximately 250mW) during active mode, a BSR node must work under an extremely low duty cycle (approximately 0.4%). This ultra-low duty cycle complicates MAC layer design because a BSR node must sleep for more than 99.6% of overall operation time. Another challenge for MAC layer design is the inability to predict when the BSR node awakens from sleep mode due to unpredictability of the harvested energy. Therefore, two feasible MAC layer designs, CSA (carrier sense ALOHA based)-MAC and GRI (gateway radio initialized)-MAC, are proposed in this thesis.

Wireless Sensor Networks (WSNs) consist of Sensor Nodes (SNs) spatially removed from one another, that can monitor a variety of environmental conditions. SNs then collaboratively communicate the collected information to a central location, by passing along the data in a multi-hop fashion. SN energy resources are limited and energy monitoring and preservation in WSNs are therefore very important. Since multi-hop communication takes place, the routing protocol used may have a significant effect on the balanced use and preservation of energy in the WSN. A significant amount of research has been performed on energy efficient routing in WSNs, but the majority of these studies were only implemented in simulation. The simulation engines used to perform these studies do not take into account all of the relevant environmental factors affecting energy efficiency. In order to comment on the feasibility of a routing protocol meant to improve the energy efficiency of a WSN, it is important to test the routing scheme in a realistic environment. In this study, a SN specifically designed to be used in an energy consumption ascertaining WSN testbed was developed. This SN has a unique set of features which makes it ideal for this application. Each SN is capable of recording its own power consumption. The design also features a lithium battery charging circuit which improves the reusability of the SN. Each node has a detachable sensor module and transceiver module which enables the researcher to conduct experiments using various transceivers and sensors. Twenty of these SNs were then used to form an energy consumption ascertaining WSN testbed. This testbed was used to compare the energy consumption of a Minimum Total Transmission Power Routing (MTTPR) scheme to a shortest hop path routing scheme. The results show that each SN’s transmission power setting dependant efficiency has a significant effect on the overall performance of the MTTPR scheme. The MTTPR scheme might in some cases use more energy than a shortest hop path routing scheme because the transmission power setting dependant efficiency of the transceiver is not taken into account. The MTTPR scheme as well as other similar routing schemes can be improved by taking the transceiver efficiency at different transmission power settings into account. Simulation environments used to evaluate these routing schemes can also be improved by considering the transceiver efficiency at different transmission power settings. / MIng (Computer and Electronic Engineering), North-West University, Potchefstroom Campus, 2014

Wireless Sensor Networks (WSNs) consist of Sensor Nodes (SNs) spatially removed from one another, that can monitor a variety of environmental conditions. SNs then collaboratively communicate the collected information to a central location, by passing along the data in a multi-hop fashion. SN energy resources are limited and energy monitoring and preservation in WSNs are therefore very important. Since multi-hop communication takes place, the routing protocol used may have a significant effect on the balanced use and preservation of energy in the WSN. A significant amount of research has been performed on energy efficient routing in WSNs, but the majority of these studies were only implemented in simulation. The simulation engines used to perform these studies do not take into account all of the relevant environmental factors affecting energy efficiency. In order to comment on the feasibility of a routing protocol meant to improve the energy efficiency of a WSN, it is important to test the routing scheme in a realistic environment. In this study, a SN specifically designed to be used in an energy consumption ascertaining WSN testbed was developed. This SN has a unique set of features which makes it ideal for this application. Each SN is capable of recording its own power consumption. The design also features a lithium battery charging circuit which improves the reusability of the SN. Each node has a detachable sensor module and transceiver module which enables the researcher to conduct experiments using various transceivers and sensors. Twenty of these SNs were then used to form an energy consumption ascertaining WSN testbed. This testbed was used to compare the energy consumption of a Minimum Total Transmission Power Routing (MTTPR) scheme to a shortest hop path routing scheme. The results show that each SN’s transmission power setting dependant efficiency has a significant effect on the overall performance of the MTTPR scheme. The MTTPR scheme might in some cases use more energy than a shortest hop path routing scheme because the transmission power setting dependant efficiency of the transceiver is not taken into account. The MTTPR scheme as well as other similar routing schemes can be improved by taking the transceiver efficiency at different transmission power settings into account. Simulation environments used to evaluate these routing schemes can also be improved by considering the transceiver efficiency at different transmission power settings. / MIng (Computer and Electronic Engineering), North-West University, Potchefstroom Campus, 2014

Master of Science / Department of Computing and Information Sciences / John M. Hatcliff / Developing a wireless sensor network application includes a variety of tasks, such as coding of the implementation, designing the architecture and assessing availability of hardware components, that provide necessary capabilities. Before compiling an application, the developer has to configure the selection of hardware components and set up required parameters. One has to choose from among a variety of configurations regarding communication parameters, such as frequency, channel, subnet identifier, transmission power, etc.. This configuration step also includes setting up parameters for the selection of hardware components, such as a specific hardware platform, which sensor boards and programmer boards to be used or the use of optional services and more. Reasoning about a proper selection of configuration parameters is often very difficult, since there are a lot of dependencies among these parameters which may rule out some other options. The developer has to know about all these constraints in order to pick a valid configuration. Unfortunately, the existing makefile approach that comes with nesC is poorly organized and does not capture important compatibility constraints. The configuration of a particular nesC application is distributed in multiple makefiles. Therefore a developer has to look at multiple files to make sure all necessary parameter are set up correctly for compiling a specific application. Furthermore without analyzing all makefiles it is unclear what the total configurability of a nesC application is and what options and parameters are provided (e.g. is there a parameter for enabling secure communication). In addition to this, the makefile approach tends to be error-prone, since the developer has to type in variable names and values manually, that match the existing implementation. However, the existing configuration system does not capture important compatibility constraints, such as capabilities of selected hardware components. This thesis proposes the use of feature models to configure nesC-based sensor network applications. We provide a tool-supported framework to model valid configurations and a generator that translates this model into a makefile compatible with existing nesC infrastructure. The framework automatically rules out selection of incompatible features using a build-in constraint language. Since all variables are defined in the model, misspellings of variable names are reduced and their domains are clearly defined because most variables come with all its possible options. A developer just needs to choose one or more of them by enabling certain features, where the problem of cardinality is also handled by the model. We show a detailed analysis of nesC's variability domain and how to use feature models to cover the exact behavior of nesC's makefile approach. In a following chapter we simplify our feature model and include the selection of specific hardware components, its capabilities and its dependencies. The feature model and the makefile generator offer a convenient way to configure nesC applications, that is faster, easier to understand and to handle, more transparent and once implemented it gives the possibility to adopt this configuration tool to an existing development environment.

Master of Science / Department of Computing and Information Sciences / David A. Gustafson / The best mode of communication for a team of mobile robots deployed to cooperatively perform a particular task is through exchange of messages. To facilitate such exchange, a communication network is required. When successful execution of the task hinges on communication, the network needs to be robust - sufficiently reliable and secure. The absence of a fixed network infrastructure defeats the use of traditional wire-based communication strategies or an 802.11-based wireless network that would require an access point. In such a case, only an ad hoc wireless network is practical. This thesis presents a robust wireless communication solution for mobile robots using motes. Motes, sometimes referred to as smart dust, are small, low-cost, low-power computing devices equipped with wireless communication capability that uses Radio Frequency (RF). Motes have been applied widely in wireless sensing networks and are typically connected to sensors and used to gather information about their environment. Communication in a mote network is inherently unreliable due to message loss, exposed to attacks, and supports very low bandwidth. Additional mechanisms are therefore required in order to achieve robust communication. Multi-hop routing must be used to overcome short signal transmission range. The ability of a mobile robot to determine its present location can be exploited in building an appropriate routing protocol. When present, information about a mobile robot's future location can aid further the routing process. To guarantee message delivery, a transport protocol is necessary. Optimal packet sizes should be chosen for best network throughput. To protect the wireless network from attacks, an efficient security protocol can be used. This thesis describes the hardware setup, software configuration, and a network protocol for a team of mobile robots that use motes for robust wireless communication. The thesis also presents results of experiments performed.

ITC/USA 2005 Conference Proceedings / The Forty-First Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2005 / Riviera Hotel & Convention Center, Las Vegas, Nevada / This paper suggests a reconfigurable sensor network (data bus) which is well suited for telemetry mission of rockets and launch vehicles. Reconfiguration of sensors’ channel information can be achieved without additional software and hardware. The proposed network consists of a central unit and multiple remote units with RS-485 data bus. Since those units need only an FPGA and a programmable ROM to be implemented, the network can provide minimum costs and high reliability. And this paper also presents reliability prediction result of a unit based on MIL-HDBK-217F and Monte Carlo simulation.

Thesis (MScEng (Electrical and Electronic Engineering))--Stellenbosch University, 2008. / There is currently a disparity in the amount of research done in underwater communication when compared to terrestrial communication. Therefore, it was the goal of this work to try and make an initial step towards bridging that gap. To start with, an introductory analysis was made of the ocean as a communications medium, focusing on any areas where the ocean characteristics could negatively affect communication. Furthermore, an overview was conducted of current communication schemes, to determine where ocean communication would differ from terrestrial communication, with the idea of determining the limiting parameters of such communication, specifically in terms of protocol design for swarms and sensor networks. Using this research, a n-ary tree-based routing algorithm was designed and incorporated into an overall protocol in line with current ISO convention. The strategy was simulated using the Erlang platform and it was found that underwater communication can be achieved with favourable results. It was however also found that using Erlang as a communications tool is currently not the best option and has various shortcomings, although with further work it could be more usable. The implemented strategy appears eminently feasible and should provide a basis for further research and practical implementation

In a domain with diverse multi-disciplinary views of what a Wireless Sensor Network (WSN) is, tracking progress and developing efficient WSNs is inherently a complex process. The main motivation of this work is advancing state-of-the-art WSNs by adaptively utilizing their components, and enlisting the utility of resources in network vicinity. As WSNs increase in density and expand in scale, we continue to witness an increase in overlapped deployments that serve independent applications. In most scenarios, new networks are deployed for new applications without considering previous or neighboring WSNs. This thesis presents the resource reuse (RR-WSN) paradigm. Adopting a generic framework for resource utilization, we achieve synergy between heterogeneous sensing systems. We abstract the view of a WSN in terms of functional capabilities, and offer a component-based view to boost sensor node (SN) potential and contribution to WSN operation. Thus SNs provide resources. On the other hand, we formally derive a set of functional requirements per application. The design and deployment of WSNs thus converges to an optimal assignment of functional requirements to resources. Two mainstream designs of WSNs are addressed in this thesis. The first involves WSNs with static deployments of nodes, whereby multiple applications run on networks in a given vicinity, yet the resources and applications share an owner (e.g., on a University Campus). We then present a Binary Integer Programming formulation to find the optimal assignment of resources to these functional requirements, while minimizing the energy impact of running each functional request. We further extend our scope to include WSNs that depend on transient nodes, such as smartphones, in a dynamic (DRR-WSN) paradigm, which could contribute significantly to the resource pool. Intuitively, multiple-owners are involved as resource providers and require different applications. Thus, we address the valuation of resources as they are shared across network owners. We finally present a maximal matching problem of finding the lowest cost for running each application, based on the available resource pool in the vicinity required. Extensive performance evaluation depicts the impact of RR-WSN design on WSN operation and longevity in various scenarios. / Thesis (Ph.D, Computing) -- Queen's University, 2013-08-27 04:44:14.556

In recent years, advances in signal processing have led to small, low power, inexpensive Wireless Sensor Network (WSN). The signal processing in WSN is different from the traditional wireless networks in two critical aspects: firstly, the signal processing in WSN is performed in a fully distributed manner, unlike in traditional wireless networks; secondly, due to the limited computation capabilities of sensor networks, it is essential to develop an energy and bandwidth efficient signal processing algorithms. Target localisation and tracking problems in WSNs have received considerable attention recently, driven by the necessity to achieve higher localisation accuracy, lower cost, and the smallest form factor. Received Signal Strength (RSS) based localisation techniques are at the forefront of tracking research applications. Since tracking algorithms have been attracting research and development attention recently, prolific literature and a wide range of proposed approaches regarding the topic have emerged. This thesis is devoted to discussing the existing WSN-based localisation and tracking approaches. This thesis includes five studies. The first study leads to the design and implementation of a triangulation-based localisation approach using RSS technique for indoor tracking applications. The presented work achieves low localisation error in complex environments by predicting the environmental characteristics among beacon nodes. The second study concentrates on investigating a fingerprinting localisation method for indoor tracking applications. The proposed approach offers reasonable localisation accuracy while requiring a short period of offline computation time. The third study focuses on designing and implementing a decentralised tracking approach for tracking multiple mobile targets with low resource requirements. Despite the interest in target tracking and localisation issues, there are few systems deployed using ZigBee network standard, and no tracking system has used the full features of the ZigBee network standard. Tracking through the ZigBee is a challenging task when the density of router and end-device nodes is low, due to the limited communication capabilities of end-device nodes. The fourth study focuses on developing and designing a practical ZigBee-based tracking approach. To save energy, different strategies were adopted. The fifth study outlines designing and implementing an energy-efficient approach for tracking applications. This study consists of two main approaches: a data aggregation approach, proposed and implemented in order to reduce the total number of messages transmitted over the network; and a prediction approach, deployed to increase the lifetime of the WSN. For evaluation purposes, two environmental models were used in this thesis: firstly, real experiments, in which the proposed approaches were implemented on real sensor nodes, to test the validity for the proposed approaches; secondly, simulation experiments, in which NS-2 was used to evaluate the power-consumption issues of the two approaches proposed in this thesis.

This thesis focuses on developing a high data rate wireless sensor network framework that could be integrated with hardware prototypes to monitor structural health of buildings. In order to better understand the wireless sensor network architecture and its consideration in structural health monitoring, a detailed literature review on wireless sensor networks has been carried out. Through research, it was found that there are numerous simulation software packages available for wireless sensor network simulation. One suitable software was selected for modelling the framework. Research showed that Matlab/Simulink was the most suitable environment, and as a result, a wireless sensor network framework was designed in Matlab/Simulink. Further, the thesis illustrates modeling of a simple accelerometer sensor, such as those used in wireless sensor networks in Matlab/Simulink using a mathematical description. Finally, the framework operation is demonstrated with 10 nodes, and data integrity is analyzed with cyclic redundancy check and transmission error rate calculations.