Animal monitoring devices are deployed by the Department of Conservation (DOC) in remote areas. Currently this requires field workers to visit each device on a regular basis, which is costly and time consuming. This report details wireless technologies that would allow remote monitoring of these devices to bring about increased operational efficiency for DOC. Of particular interest is the wireless transmission of images through forested terrain. While traditionally recognised as a difficult environment for wireless communications, research undertaken has indicated transmissions at 27 MHz are capable of achieving the feat. Development of a working system is greatly reduced through the use of Slow Scan Television technology; however justification for the system requires further study into particular case studies.

Recently, stochastic geometry has been shown to be a very powerful tool to model, analyze, and design networks with random topologies such as wireless ad hoc and sensor networks as well as multi-tier cellular networks. In stochastic geometry analysis, point processes are used to model the positions and the channel access behaviors of the nodes. The thesis develops analytical frameworks to characterize the performance of large-scale wireless networks with random topologies. In particular, I use stochastic geometry tools to model, analyze, and design ad hoc networks, star-connected sensor networks, and infrastructure-based two-tier cellular networks. I have optimized the tradeoff between outage probability and spatial frequency reuse efficiency in carrier sensing-multiple-access based ad hoc networks. I have developed a novel spectrum efficient design paradigm for star-connected wireless sensor networks. For downlink transmission in cellular networks with cognitive femto access points (FAPs), I have quantified the performance gain imposed by cognition and developed a paradigm to optimize the spectrum sensing threshold for cognitive FAPs. Finally, I have developed a novel modeling paradigm for uplink transmission in cellular networks and obtained simple expressions for network performance metrics including the outage probability and average rate. Furthermore, I have revealed a transition point in the behavior of uplink transmission in cellular networks that depends on the relative values of the network parameters.

As the demand for cheaper electronic devices has increased, the location of manufacturing foundries has changed to untrusted places outside of the United States. Some of these locations have limited oversight of the manufacturing of complicated and sensitive electronic components including integrated circuits (IC). IC, a key component in all current electronic devices, can be modified to be malicious or to monitor the functions of their applications. These malicious modifications are called Hardware Trojans. Hardware Trojans can be de- signed to quietly monitor, to actively send out unencrypted sensitive information, or to actively destroy their host device. Our research demonstrates the ability of Hardware Trojans to infiltrate a sensor network that could be remotely deployed for various applications. This research is important due to the dearth of knowledge on the subject. Currently, software security is given great importance. Our research shows that the same level of importance must be given to hardware to ensure a trusted and secure environment.

Testing plays an important role in the wireless protocol stack development. In order to free the testers out of the shielded chamber, allow both the developers and the testers to use the test systems remotely and maximize the expensive test system usage. An automated test framework is highly demanded. In this thesis, the design of the automated test framework is introduced. There are four main components in the test framework. They are the front end, scheduler, test engine and data storage. The architecture and the protocol among these components are described. Further, the evaluation of the scheduler is conducted based on the queueing theory. Based on the simulation result, a good scheduling algorithm is proposed. Compared with the original scheduling algorithm, the new algorithm improves the performance of the low priority users significantly when the test systems are limited. Moreover, the detail design of the test engine is presented. With the control of the intelligent test engine, the automated test framework has the capability to launch the test cases automatically, catch the commands sent by the test system and manipulate the SUT (System Under Test) without human’s interrupt. It fulfills the objective of automation. The automated test framework has been deployed and is working well.

An understanding of network traffic behavior is essential in the evolution of today's wireless networks, and thus leads to a more efficient planning and management of the network's scarce bandwidth resources. Prior reservation of radio resources at the future locations of a user's mobile travel path can assist with optimizing the allocation of the network's limited resources. Such actions are intended to support the network with sustaining a desirable Quality-of-Service (QoS) level. To help ensure the availability of the network services to its users at anywhere and anytime, there is the need to predict when and where a user will demand any network usage. In this thesis, the mobility behavior of the wireless users are modeled as a Markov renewal process for predicting the likelihoods of the next-cell transition. The model also includes anticipating the duration between the transitions for an arbitrary user in a wireless network. The proposed prediction technique is further extended to compute the likelihoods of a user being in a particular state after $N$ transitions. This technique can also be applied for estimating the future spatial-temporal traffic load and activity at each location in a network's coverage area. The proposed prediction method is evaluated using some real traffic data to illustrate how it can lead to a significant improvement over some of the conventional methods. The work considers both the cases of mobile users with homogeneous applications (e.g. voice calls) and data connectivity with varying data loads being transferred between the different locations.

Modern wireless telecommunication devices (GSM Mobile system) (cellular telephones and wireless modems on laptop computers) have the potential to interfere with implantable medical devices/prostheses and cause possible malfunction. An implant of resonant dimensions within a homogeneous dielectric lossy sphere can enhance local values of SAR (the specific absorption rate). Also antenna radiation pattern and other characteristics are significantly altered by the presence of the composite dielectric entities such as the human body. Besides, the current safety limits do not take into account the possible effect of hot spots arising from metallic implants resonant at mobile phone frequencies. Although considerable attention has been given to study and measurement of scattering from a dielectric sphere, no rigorous treatment using electromagnetic theory has been given to the implanted dielectric spherical head/cylindrical body. This thesis aims to deal with the scattering of a plane electromagnetic wave from a perfectly conducting or dielectric spherical/cylindrical implant of electrically small radius (of resonant length), embedded eccentrically into a dielectric spherical head model. The method of dyadic Green's function (DGF) for spherical vector wave functions is used. Analytical expressions for the scattered fields of both cylindrical and spherical implants as well as layered spherical head and cylindrical torso models are obtained separately in different chapters. The whole structure is assumed to be uniform along the propagation direction. To further check the accuracy of the proposed solution, the numerical results from the analytical expressions computed for the problem of implanted head/body are compared with the numerical results from the Finite-Difference Time-Domain (FDTD) method using the EMU-FDTD Electromagnetic simulator. Good agreement is observed between the numerical results based on the proposed method and the FDTD numerical technique. This research presents a new approach, away from simulation work, to the study of exact computation of EM fields in biological systems. Its salient characteristics are its simplicity, the saving in memory and CPU computational time and speed.

Low cost, low power wireless sensors (motes) promise to revolutionize environmental data collection, but are they currently refined enough for widespread use by hydrologists? Their viability as a replacement for traditional data collection techniques was investigated in a 7 ha forested watershed in south-western British Columbia. The watershed included 41 instrument clusters measuring air and soil temperature, humidity, throughfall, soil moisture content, overland flow and groundwater head. The foundation of each cluster was a data box containing a MDA300 data acquisition board and a MICA2 processor board from Crossbow Technologies, Inc.™ that allowed for short range wireless data collection. The 41 motes each recorded data every 15 minutes from July, 2006, to April, 2007. In addition to reporting on the reliability of the motes and sensors during the 10 months deployment, the high spatial and temporal resolution data collected by this study gave the opportunity for many analyses of catchment processes. As soil moisture and throughfall are two influential processes in the exchange of water between the earth and the atmosphere, these were the focus of the data analysis. The first analysis was a resampling experiment on seven different events selected from the full data set. Comparing 100 different subsamples each of 5, 10 and 20 points for throughfall and soil moisture showed if increasing the sample size eventually produced diminishing returns in the ability to reproduce the true catchment mean. With significant differences in prediction ability for both soil moisture and throughfall at times of differing hydrologic activity, this analysis provides further support for the theories of changing moisture states of soil moisture and threshold values for throughfall. The second analysis described how the organization of soil moisture and throughfall changed during a range of weather conditions and timescales. Spatial representation of normalized values and Pearson correlation coefficients showed that there were distinct differences between wet and dry periods for soil moisture and between long and short analysis periods for throughfall.

This thesis focuses on the issues in transport protocol performance in wireless ad-hoc networks.From the review of existing research we identify the following three main factors contributing to the poor performance of transport protocols such as TCP. These are: the inability of transport protocol to detect/identify and respond to network events in wireless ad-hoc networks; the inability of TCP window-based flow control mechanism to avoid overloading the wireless channel; and the frequent route failures due to mobility, causing interruptions in transmission. / We focus on 2 mechanisms to improve the performance of transport protocols. Recognising the many benefits of multipath routing in wireless ad-hoc networks, we propose a multipath transport design framework, incorporating a number of transport protocol components that are suitable for wireless ad-hoc networks, with different degrees of cross-interference. We first consider the use of independent multiple paths, and show that the throughput performance of multiple paths is no more than 55-60%, due to a spatial reuse of the wireless channel at the source. We then show that the overall improvement resulting from the use of independent multiple paths is further limited by the scarcity of independent multiple paths between a given pair of source and destination nodes. We conclude that independent multipaths are worth consideration only in sufficiently dense and large networks. Then we propose metrics to characterise node-disjoint multipaths with different degrees of cross-interference, and investigate correlation of these metrics with the throughput performance of multipath. / Our simulation results show that the throughput performance of multiple paths is determined by both the number of cross-interference links between paths and the local density of cross path links. These observations can be used in selecting multiple paths for good throughput performance of multipath transport. / The second mechanism we focus on is the rate-based flow control over a multi-hop path. Recognising the lack of suitable bandwidth estimation techniques for multi-hop wireless networks, we propose a new bandwidth estimation technique (termed Saturation Throughput Estimate or STE) suitable for wireless ad-hoc networks. It is based on a nearly linear relationship between channel occupancy (a local measurement of the channel activity level) and throughput available to a node. It also accounts for the traffic forwarded by the neighbouring nodes on behalf of the node in question. We show that our estimation technique is capable of providing good estimates of bandwidth available to a node in small to medium size ad-hoc networks, over a broad range of traffic loads. We also develop and verify an analytical model of IEEE 802.11 suitable for studying 802.11 performance under limited load conditions. Our analytical studies confirm the key assumption of a nearly linear relationship between channel occupancy and throughput underlying the proposed STE bandwidth estimation technique, and provide useful insights into selecting a suitable operating point to achieve high channel utilisation and avoid congestion in the wireless channel. Subsequently, the proposed STE bandwidth estimation technique is fine-tuned to meet the requirements of rate-based flow control over a multi-hop path. Finally, we present and develop a design of a feedback rate-based flow control framework to evaluate the merit of our STE technique and other rate estimation techniques proposed in the subject literature. We show that ATP (Ad-Hoc Transport Protocol) rate estimation technique tends to saturate the network, resulting in long queuing delay. In contrast, the rate-based flow control scheme using our STE rate estimate as rate feedback is effective in regulating and maintaining traffic just below the congestion point, thus achieving high network utilisation in static and low mobility networks. / Thesis (PhDTelecommunications)--University of South Australia, 2006.

Multicast is an efficient way of disseminating information to a group of receivers on the Internet and other computer networks. To combat losses, transmission repetition is common in both best effort and reliable multicast protocols. In the latter, repetition is performed by an automatic repeat request (ARQ) scheme. In either case, forward error correction (FEC) coding can be used to replace repetition, which may result in remarkably improved performance in terms of user throughput. This improvement is especially significant for wireless networks where bandwidth is valuable and loss rate is high. The main goal of this research is to find efficient FEC and hybrid FEC/ARQ (known as HARQ) schemes for a class of message-based multicast protocols, which are compatible with the protocols operating in a wireless environment. / In this thesis, firstly, general multicast and error control techniques are reviewed and examined. A message-based multicast protocol P_Mul is used as a base for performance studies and protocol modifications. P_Mul is designed to handle receivers operating in responsive and silent (no feedback) operational modes. An OPNET model of the standard P_Mul error recovery scheme, originally based on ARQ, is developed. Various schemes such as an ideal (rateless) FEC, Reed-Solomon and LDPC codes are incorporated in the model and their behaviours simulated, discussed and compared with the standard P_Mul performance. / Novel message-based mathematical models are derived that allow accurate estimation of P_Mul performance in the case of finite-length message multicast. The mathematical models take into account certain scenarios and schemes, e.g. when loss is random and all receivers non-responsive or responsive with error recovery based on ARQ or its hybrid with ideal FEC. / Furthermore, the simulation model is expanded so that P_Mul can efficiently manage complex traffic with different priorities; seamlessly serve multicast groups whose members may change operational modes frequently; and adapt to the channel conditions without saturating the network with an excessive number of packets. The performance of the P_Mul model with various enhancements is progressively simulated, compared and argued, pointing to the influence of the various protocol and network parameters. / Finally, a novel method for improving the performance of short messages at high error rates is proposed and the preliminary performance analysed. The method applies erasure decoding on smaller payload portions, called packet segments, to better match with the high error rates, yet without shortening the packet to the lower layer. With some increase in processing complexity and error detection overhead, the chance of short message reception improves considerably / Thesis (PhDTelecommunications)--University of South Australia, 2005.

This thesis addresses the performance evaluation and enhancement of wireless networks. Part I investigates the problem of resource allocation in cellular networks, focusing on handoff, and Part II investigates resource allocation in sensor networks focusing on power management. (For complete abstract open document)