Over the past decade, wireless sensor networks have gained more research attention for their potential applications in healthcare, defense, environmental monitoring, etc. Due to the strict energy limitation in the sensor node, techniques used for energy saving are necessary for this kind of network. MIMO technology is proven to be an effective method of increasing the channel capacity and supporting higher data rate under a fixed power budget and bit-error-rate requirement. So, wireless sensor networks and MIMO technology are combined and investigated in this thesis. The key contributions of this thesis are detailed below. Firstly, the extended total energy consumption equations for different transmission modes in cluster-based wireless sensor networks are derived. The transmitting energy consumption and the circuit energy consumption are taken into account in both intra-cluster and inter-cluster phases respectively. Secondly, a resource allocation framework is proposed for cluster-based cooperative MIMO on consideration of circuit energy. By introducing two adjusting parameters for the transmitting energy and the time slot allocation between intra-cluster and inter-cluster phases, this framework is designed to achieve the maximum data throughput of the whole system whilst maintaining the capacity and outage probability requirement in these two phases respectively. Thirdly, on comparison of various transmission modes in wireless sensor networks, a relatively energy-efficient mode switching framework is proposed for both single-hop and multi-hop transmissions. Based on the destination and the neighboring nodes’ path-loss, the source node can decide which transmission mode, SISO or cooperative MISO, single-hop or multi-hop, should be chosen. Conditions for each mode switching are investigated. The possible existing area of the cooperative nodes and the relaying nodes can be obtained from this framework.

Approved for public release; distribution unlimited / This thesis investigates the fundamentals of Multiple-Input-Multiple-Output (MIMO) radio communication systems with space-time codes. A MIMO system was design using the Alamouti space-time code. The modulation technique was binary phase-shift keying (BPSK). Matlab with Simulink was used to simulate the design, which was tested in both an additive white Gaussian noise (AWGN) channel and in a multipath fading channel with AWGN. Theoretical performance was derived for both channels and compared to simulated results. The original receiver design was changed to incorporate a maximal-ratio combiner (MRC) receiving technique with channel state information (CSI). The theoretical performance for this design was determined and compared to simulated and published results. / Lieutenant Commander, Canadian Navy

With the ever increasing popularity of wireless internet, its scale is broadening. While the IEEE 802.15 standard provides the parameters necessary for a wireless personal area network (WPAN), the IEEE 802.16a standard provides broadband wireless access (BWA), or a wireless metropolitan area network (WMAN). Popularly referred to as Wi Max, the standard uses cellular topography with a base station and subscriber station and cuts down on infrastructure and thus can be used in most environments. The 802.16a standard can take advantage of the popular OFDM modulation technique. This thesis takes a developed synchronization algorithm and tests its performance on 802.16a. In addition, it tests the standard's performance in different types of channel. Various techniques are evaluated including interleaving and antenna diversity. The 802.16a standard employs a form of transmit diversity called Space Time Coding. The transmit diversity is compared with Maximal Ratio Combining receiver diversity. The evaluation was done in simulation developed in Matlab; the simulations show drastic improvement when using the aforementioned techniques, particularly diversity.

Wireless Sensor Networks (WSNs) is an important field of study as more and more applications are enhancing daily life. The technology trend is to achieve small-sized, cheap, and power efficient sensor nodes, which will make the system reliable and efficient. The Crossbow Technologies MICAz mote is an example used in this thesis. Measurements for its propagation characteristics in a realistic environment will help the deployment and installation of these motes to form a WSN. The CST Microwave Studio is used to build a simulation for the MICAz. The Rhino software is used to build Spanagel Hall, which is the location of the simulation. All of these elements are integrated in Urbana. Urbana is a simulation tool used to simulate the propagation decay around the mote and investigate the irregularity of the electromagnetic field for the indoor environment of the motes. The results and comparisons between empirical and simulated data are intended for assisting in the design and future studies and deployment of WSNs in the real world. / Jordanian Army author.

Dense deployment of small cells underlaying the traditional macrocells is considered as a key enabling technique for the emerging fifth generation (5G) cellular networks. However, the diverse transmit powers of the base stations (BSs) in such a network lead to uneven distribution of the traffic loads among different BSs when received signal power (RSP)-based user association is used. Moreover, provisioning of efficient and economical backhauling for these small cells is a crucial challenge. To combat this, wireless backhauling is been considered as a viable and cost-effective approach that allows operators to obtain end-to-end control of their network rather than leasing third party wired backhaul connections. But the scarcity of radio frequency (RF) spectrum in the licensed bands is still a major constraint which necessitates efficient spectrum planning for backhaul/access links of small cells. Emerging communications techniques such as full-duplexing, which allows transmission and reception in the same spectrum band, can be used to tackle the problem of spectrum scarcity. In the above contexts, the objective of the research work presented in this thesis is to develop efficient user association and wireless backhauling schemes for small cell networks and analyze their performances. In particular, i) A channel-access aware user association scheme is proposed to tackle the problem of uneven distribution of traffic load among different BSs, ii) Performance analysis of full-duplex (FD) wireless backhauling of small cells is carried out when compared to half-duplex (HD) wireless backhauling), iii) A method for downlink spectrum allocation for in-band and out-of-band wireless backhauling of full-duplex small cells is presented to optimally allocate spectrum for access and backhaul links, iv) A method for optimal channel and power allocation is presented for downlink access and backhaul links for half-duplex small cells. The proposed methods and performance analysis models will be useful for optimizing the design and deployment of small cell networks. / October 2017

A passive wireless sensor is designed, fabricated and tested for the measurement of AC electric field in the vicinity of high voltage apparatus. This sensor is applicable in remote condition monitoring of high voltage apparatus where close distance measurements raises safety hazards for operators. The sensor is designed using a coaxial cavity resonator structure (in TEM mode) capacitively coupled to varactors. The resonance frequency of the sensor shifts corresponding to the capacitance variation of the varactors which in turn is perturbed by the external electric field. The electric field surrounding the apparatus induces a bias voltage over the terminals of the varactors. Therefore, the resonance frequency changes proportional to the inducing external electric field and correspondingly to the medium/high voltage. A printed circuit board on the top of the cavity provides coupling between the cavity and varactors and also between the varactors and the external field produced by the high voltage apparatus. The sensor structure is designed to resonate in the range of 2.4 GHz to 2.5 GHz of the industrial, scientific and medical (ISM) radio frequency band. A remote interrogation system identifies the instantaneous resonance frequency of the sensor by transmitting pulses of radio frequency (RF) signal and recording the ring back of the resonator. The ring back is down converted and analyzed to determine the resonance frequency of the sensor. Two possible applications of the sensor, i.e. voltage measurement and defect detection of insulators, are demonstrated by experimental results. / February 2017

In this dissertation, we discuss throughput-optimal scheduling design in multiuser wireless networks. Throughput-optimal scheduling algorithm design in wireless systems with flow-level dynamics is a challenging open problem, especially considering that the majority of the Internet traffic are short-lived TCP controlled flows. In future wireless networks supporting machine-to-machine and human-to-human applications, both short-lived dynamic flows and long-lived persistent flows coexist. How to design the throughput-optimal scheduling algorithm to support dynamic and persistent flows simultaneously is a difficult and important unsolved problem. Our work starts from how to schedule short-lived dynamic flows in wireless systems to achieve throughput-optimality with queue stability. Classic throughput-optimal scheduling algorithms such as the Queue-length based Maxweight scheduling algorithm (QMW) cannot stabilize systems with dynamic flows in practical communication networks. We propose the Head-of-Line (HOL) access delay based scheduling algorithm (HAD) for flow-level dynamic systems, and show that HAD is able to obtain throughput-optimality which is validated by simulation. As the Transmission Control Protocol (TCP) is the dominant flow and congestion control protocol for the Internet nowadays, we turn our attention to the compatibility between throughput-optimal schedulers and TCP. Most of the existing throughput-optimal scheduling algorithms have encountered unfairness problem in supporting TCP-controlled flows, which leads to undesirable network performance. Motivated by this, we first reveal the reason of the unfairness problem, then study the compatibility between HAD and TCP with different channel assumptions, and finally analyze the mean throughput performance of HAD. The result shows that HAD is compatible with TCP. Since the assumption of an infinite buffer size in the existing theoretical analysis of throughput-optimality is not practical, we analyze the queueing behaviour of the proposed throughput-optimal scheduling algorithm to provide useful guidelines for real system design by using the Markov chain analytic model. We propose the analytic model for the queuing and delay performance for the HAD scheduler, and then further develop an approximation approach to reduce the complexity of the model. Finally, we propose a throughput-optimal scheduling algorithm for hybrid wireless systems with the coexistence of persistent and dynamic flows. Then, to generalize the throughput-optimal scheduling, the control function in the scheduling rule is extended from a specific one to a class of functions, so that the scheduling design can be more flexible to make a tradeoff between delay, fairness, etc. We show that the hybrid wireless networks with coexisting persistent flows and dynamic flows can be stabilized by our proposed scheduling algorithm which can obtain throughput-optimality. In summary, we solve the challenging problem of designing throughput-optimal scheduling algorithm in wireless systems with flow-level dynamics. Then we show that our algorithm can support TCP regulated flows much better than the existing throughput-optimal schedulers. We further analyze the queueing behaviour of the proposed algorithm without the assumption of infinite buffer size that is often used in the throughput-optimality analysis in the literature, and the result provides a guideline for the implementation of our algorithm. At last, we generalize the proposed scheduling algorithm to support different types of flows simultaneously in practical wireless networks. / Graduate / chenyi.nwpu@gmail.com

Robots have long been used for completing tasks that are too difficult, dangerous, or distant to be accomplished by humans. In many cases, these robots are highly specialized platforms - often expensive and capable of completing every task related to a mission's objective. An alternative approach is to use multiple platforms, each less capable in terms of number of tasks and thus significantly less complex and less costly. With advancements in embedded computing and wireless communications, multiple such platforms have been shown to work together to accomplish mission objectives. In the extreme, collections of very simple robots have demonstrated emergent behavior akin to that seen in nature (e.g., bee colonies) motivating the moniker of ''swarm robotics'' - a group of robots working collaboratively to accomplish a task. The use of robotic swarms offers the potential to solve complex tasks more efficiently than a single robot by introducing robustness and flexibility to the system. This work investigates localization in heterogeneous and autonomous robotic swarms to improve their ability to carry out exploratory missions in unknown terrain. Collaboratively, these robots can, for example, conduct sensing and mapping of an environment while simultaneously evolving a communication network. For this application, among many others, it is required to determine an accurate knowledge of the robot's pose (i.e., position and orientation). The act of determining the pose of the robot is known as localization. Some low cost robots can provide location estimates using inertial measurements (i.e., odometry), however this method alone is insufficient due to cumulative errors in sensing. Image tracking and wireless localization methods are implemented in this work to increase the accuracy of localization estimates. These localization methods complement each other: image tracking yields higher accuracy than wireless, however a line-of-sight (LOS) with the target is required; wireless localization can operate under LOS or non-LOS conditions, however has issues in multipath conditions. Together, these methods can be used to improve localization results under all sight conditions. The specific contributions of this work are: (1) a concept of 'shared sensing' in which extremely simple and inexpensive robots with unreliable localization estimates are used in a heterogeneous swarm of robots in a way that increases the accuracy of localization for the simple agents and simultaneously extends the sensing capabilities of the more complex robots, (2) a description, evaluation, and discussion of various means to estimate a robot's pose, (3) a method for increasing reliability of RSSI measurements for wireless ranging/localization systems by averaging RSSI measurements over both time and space, (4) a process for developing an in-field model to be used for estimating the location of a robot by leveraging the existing wireless communication system.

This thesis examines the use of modelling approaches in Wireless Sensor Networks (WSNs) at node and sink to: reduce the amount of data that needs to be transmitted by each node and estimate sensor readings for locations where no data is available. First, to contextualise the contributions in this thesis, a framework for WSN monitoring applications (FieldMAP) is proposed. FieldMAP provides a structure for developing monitoring applications that advocates the use of modelling to improve the informational output of WSNs and goes beyond the sense- and-send approach commonly found in current, elded WSN applications. Rather than report raw sensor readings, FieldMAP advocates the use of a state vector to encapsulate the state of the phenomena sensed by the node. Second, the Spanish Inquisition Protocol (SIP) is presented. SIP reduces the amount of data that a sensor node must transmit by combining model-based ltering with Dual-Prediction approaches. SIP makes use of the state vector component of FieldMAP to form a simple predictive model that allows the sink to estimate sensor readings without requiring regular updates from the node. Transmissions are only made when the node detects that the predictive model no longer matches the evolving data stream. SIP is shown to produce up to a 99% reduction in the number of samples that require transmission on certain data sets using a simple linear approach and consistently outperforms comparable algorithms when used to compress the same data streams. Furthermore, the relationship between the user-specied error threshold and number of transmissions required to reconstruct a data set is explored, and a method to estimate the number of transmissions required to reconstruct the data stream at a given error threshold is proposed. When multiple parameters are sensed by a node, SIP allows them to be combined into a single state vector. This is demonstrated to further reduce the number of model updates required compared to processing each sensor stream individually. iii Third, a sink-based, on-line mechanism to impute missing sensor values and predict future readings from sensor nodes is developed and evaluated in the context of an on-line monitoring system for a Water Distribution System (WDS). The mechanism is based on a machine learning approach called Gaussian Process Regression (GPR), and is implemented such that it can exploit correlations between nodes in the network to improve predictions. An on-line windowing algorithm deals with data arriving out of order and provides a feedback mechanism to predict values when data is not received in a timely manner. A novel approach to create virtual sensors that allows a data stream to be predicted where no physical sensor is permanently deployed is developed from the on-line GPR mechanism. The use of correlation in prediction is shown to improve the accuracy of predicted data from 1.55 Pounds per Square Inch (PSI) Root Mean Squared Error (RMSE) to 0.01 PSI RMSE. In-situ evaluation of the Virtual Sensors approach over 36 days showed that an accuracy of 0:75 PSI was maintained. The protocols developed in this thesis present an opportunity to improve the output of environmental monitoring applications. By improving energy consumption, long-lived networks that collect detailed data are made possible. Furthermore, the utility of the data collected by these networks is increased by using it to improve coverage over areas where measurements are not taken or available.

Approved for public release; distribution is unlimited / As mobile computing becomes more ubiquitous, through the use of very capable mobile computing devices and broadband wide area wireless data networks, naval aviation maintenance has an opportunity to extend the reach of the Naval Aviation Logistics Command Management Information System (NALCOMIS) to fielded aircrew, maintenance technicians, and maintenance supervisors supporting out of local area operations. The combination of the new mobile technologies and the wireless Internet makes modern Mobile Business (m-business) initiatives possible but ushers in a host of new problems and issues that are radically different from those experienced with traditional fixed electronic business (e-business) projects. This thesis examines the concept and components that comprise m-business, details wide area data over cellular technologies, and identifies problems and issues unique to m-business initiatives. Scenario-based Use Cases will be employed within the Unified Process (UP) framework to develop the three major artifacts of the UP's inception phase - the project's vision, a Use Case model, and a supplemental specification containing functional and non-functional requirements for an aircrew mobile aircraft maintenance application. The results of this study can serve as the foundation for the development of a complete mobile aircraft maintenance office. / Lieutenant Commander, United States Navy