Adoption of vehicular ad hoc networking protocols by networked robots

This paper focuses on the utilization of wireless networking in the robotics domain. Many researchers have already equipped their robots with wireless communication capabilities, stimulated by the observation that multi-robot systems tend to have several advantages over their single-robot counterparts. Typically, this integration of wireless communication is tackled in a quite pragmatic manner, only a few authors presented novel Robotic Ad Hoc Network (RANET) protocols that were designed specifically with robotic use cases in mind. This is in sharp contrast with the domain of vehicular ad hoc networks (VANET). This observation is the starting point of this paper. If the results of previous efforts focusing on VANET protocols could be reused in the RANET domain, this could lead to rapid progress in the field of networked robots. To investigate this possibility, this paper provides a thorough overview of the related work in the domain of robotic and vehicular ad hoc networks. Based on this information, an exhaustive list of requirements is defined for both types. It is concluded that the most significant difference lies in the fact that VANET protocols are oriented towards low throughput messaging, while RANET protocols have to support high throughput media streaming as well. Although not always with equal importance, all other defined requirements are valid for both protocols. This leads to the conclusion that cross-fertilization between them is an appealing approach for future RANET research. To support such developments, this paper concludes with the definition of an appropriate working plan

Scalable wireless sensor networks for dynamic communication environments: simulation and modelling

This thesis explores the deployment of Wireless Sensor Networks (WSNs) on localised maritime events. In particular, it will focus on the deployment of a WSN at sea and estimating what challenges derive from the environment and how they affect communication. This research addresses these challenges through simulation and modelling of communication and environment, evaluating the implications of hardware selection and custom algorithm development. The first part of this thesis consists of the analysis of aspects related to the Medium Access Control layer of the network stack in large-scale networks. These details are commonly hidden from upper layers, thus resulting in misconceptions of real deployment characteristics. Results show that simple solutions have greater advantages when the number of nodes within a cluster increases. The second part considers routing techniques, with focus on energy management and packet delivery. It is shown that, under certain conditions, relaying data can increase energy savings, while at the same time allows a more even distribution of its usage between nodes. The third part describes the development of a custom-made network simulator. It starts by considering realistic radio, channel and interference models to allow a trustworthy simulation of the deployment environment. The MAC and Routing techniques developed thus far are adapted to the simulator in a cross-layer manner. The fourth part consists of adapting the WSN behaviour to the variable weather and topology found in the chosen application scenario. By analysing the algorithms presented in this work, it is possible to find and use the best alternative under any set of environmental conditions. This mechanism, the environment-aware engine, uses both network and sensing data to optimise performance through a set of rules that involve message delivery and distance between origin and cluster hea

Wireless Sensors for Health Monitoring of Marine Structures and Machinery

Remote structural and machinery health monitoring (SMHM) of marine structures such as ships, oil and gas rigs, freight container terminals, and marine energy platforms can ensure their reliability. However, the wired sensors currently used in these applications are difficult and expensive to install and maintain. Wireless Sensor Networks (WSN) can potentially replace them but there are significant capability gaps that currently prevent their long-term deployment in the harsh marine environment and the structurally-complex, compartmentalised, all-metal scenarios with high volume occupancy of piping, ducting and operational machinery represented by marine structures. These gaps are in sensing, processing and communication hardware and firmware capabilities, reduction of power consumption, hardware assembly and packaging for reliability in the marine environment, reliability of wireless connectivity in the complex metal structures, and software for WSN deployment planning in the marine environment. Taken together, these gaps highlight the need for a systems integration methodology for marine SMHM and this is the focus of the research presented in this thesis. The research takes an applied approach by first designing the hardware and firmware for two wireless sensing modules specifically for marine SMHM, one a novel eddy-current-based 3D module for measuring multi-axis metal structural displacement, the second a fully integrated module for monitoring of structure and machinery reliability. The research then addresses module assembly and packaging methods to ensure reliability in the marine environment, the development of an efficient methodology for characterising the reliability of wireless connectivity in complex metal structures, and development of user interface software for planning WSN deployment and for managing the collection of WSN data. These are then individually and collectively characterised and tested for performance and reliability in laboratory, land-based and marine deployments. In addition to the research outcomes in each of these individual aspects, the overall research outcome represents a systems integration methodology that now allows deployment, with a high expectation of reliability of marine SMHM WSNs

Wireless sensor networks using network coding for structural health monitoring

Wireless Sensor Networks (WSNs) have been deployed for the purpose of structural health monitoring (SHM) of civil engineering structures, e.g. bridges. SHM applications can potentially produce a high volume of sensing data, which consumes much transmission power and thus decreases the lifetime of the battery-run networks. We employ the network coding technique to improve the network efficiency and prolong its lifetime. By increasing the transmission power, we change the node connectivity and control the number of nodes that can overhear transmitted messages so as to hopefully realize the capacity gain by use of network coding. In Chapter 1, we present the background, to enable the reader to understand the need for SHM, advantages and drawbacks of WSNs and potential the application of network coding techniques has. In Chapter 2 we provide a review of related research explaining how it relates to our work, and why it is not fully applicable in our case. In Chapter 3, we propose to control transmission power as a means to adjust the number of nodes that can overhear a message transmission by a neighbouring node. However, too much of the overhearing by high power transmission consumes aggressively limited battery energy. We investigate the interplay between transmission power and network coding operations in Chapter 4. We show that our solution reduces the overall volume of data transfer, thus leading to significant energy savings and prolonged network lifetime. We present the mathematical analysis of our proposed algorithm. By simulation, we also study the trade-offs between overhearing and power consumption for the network coding scheme. In Chapter 5, we propose a methodology for the optimal placement of sensor nodes in linear network topologies (e.g., along the length of a bridge), that aims to minimise the link connectivity problems and maximise the lifetime of the network. Both simple packet relay and network coding are considered for the routing of the collected data packets towards two sink nodes positioned at both ends of the bridge. Our mathematical analysis, verified by simulation results, shows that the proposed methodology can lead to significant energy saving and prolong the lifetime of the underlying wireless sensor network. Chapter 6 is dedicated to the delay analysis. We analytically calculate the gains in terms of packet delay obtained by the use of network coding in linear multi-hop wireless sensor network topologies. Moreover, we calculate the exact packet delay (from the packet generation time to the time it is delivered to the sink nodes) as a function of the location of the source sensor node within the linear network. The derived packet delay distribution formulas have been verified by simulations and can provide a benchmark for the delay performance of linear sensor networks. In the Chapter 7, we propose an adaptive version of network coding based algorithm. In the case of packet loss, nodes do not necessary retransmit messages as they are able to internally decide how to cope with the situation. The goal of this algorithm is to reduce the power consumption, and decrease delays whenever it can. This algorithm achieves the delay similar to that of three-hop direct-connectivity version of the deterministic algorithm, and consumes power almost like one-hop direct-connectivity version of deterministic algorithm. In very poor channel conditions, this protocol outperforms the deterministic algorithm both in terms of delay and power consumption. In Chapter 8, we explain the direction of our future work. Particularly, we are interested in the application of combined TDMA/FDMA technique to our algorithm.Open Acces

ReSCon '11, Research Student Conference: Book of Abstracts

The fourth SED Research Student Conference (ReSCon2011) was hosted over three days, 20-22 June 2011, in the Hamilton Centre at Brunel University. The conference consisted of technical presentations, a poster session and social events. which focused on current research being conducted within the School of Engineering and Design by postgraduate research students from the School. The conference is held annually, and ReSCon plays a key role in contributing to research and innovations within the School

An architecture framework for enhanced wireless sensor network security

This thesis develops an architectural framework to enhance the security of Wireless Sensor Networks (WSNs) and provides the implementation proof through different security countermeasures, which can be used to establish secure WSNs, in a distributed and self-healing manner. Wireless Sensors are used to monitor and control environmental properties such as sound, acceleration, vibration, air pollutants, and temperature. Due to their limited resources in computation capability, memory and energy, their security schemes are susceptible to many kinds of security vulnerabilities. This thesis investigated all possible network attacks on WSNs and at the time of writing, 19 different types of attacks were identified, all of which are discussed including exposures to the attacks, and the impact of those attacks. The author then utilises this work to examine the ZigBee series, which are the new generation of wireless sensor network products with built-in layered security achieved by secure messaging using symmetric cryptography. However, the author was able to uniquely identify several security weaknesses in ZigBee by examining its protocol and launching the possible attacks. It was found that ZigBee is vulnerable to the following attacks, namely: eavesdropping, replay attack, physical tampering and Denial of Services (DoS). The author then provides solutions to improve the ZigBee security through its security schema, including an end-to-end WSN security framework, architecture design and sensor configuration, that can withstand all types of attacks on the WSN and mitigate ZigBee’s WSN security vulnerabilities

Acoustic signal-based underwater oil leak detection and localization

Underwater Wireless Sensor Networks (UWSNs) have been becoming popular for exploring offshore, natural resource development, geological oceanography, and monitoring the underwater environment. The acoustic channel characteristics in underwater impose challenges, including limited bandwidth, signal attenuation, and propagation delay that limits UWSN utilization. The marine environment is under threat from pollution, which impacts human life and activities. Compared to other pollution types, the oil leak is a significant threat to the marine ecosystem. When the leaked oil or other petroleum products mix with water in the ocean, significant biological and economic impacts could result. Although much research has focused on improving the reception and processing of acoustic signals, increasing performance, and reducing packet delay, no significant research results have been reported on finding an effective early-stage leak detection method using acoustic signal processing. Accurate information about oil spill location and its characteristics is much needed for oil spill containment and cleanup operations. Developing an efficient under- water oil leak detection and localization algorithm is still challenging in UWSNs because of the impairments of the acoustic channel. In this thesis, we propose a technique that detects the presence of an oil leak in the underwater environment at an early stage. We also propose a localization algorithm that determines the approximate location of the oil leak. Firstly, we review the propagation properties of acoustic signals to understand acoustic communication in the marine environment better. We then discuss the transmission of sound in terms of reflection and refraction. We propose a leak detection technique based on the range estimation method to detect oil leak at an early stage before reaching the ocean sur- face. We perform a two-dimensional analysis for evaluating the performance of the proposed detection technique. To investigate the proposed technique, we perform evaluation with different network sizes and topologies. We discuss the detection ratio, network scalability, power and intensity of the received signal. We then perform a three-dimensional analysis to evaluate the performance of the proposed technique. We conduct theoretical analysis to investigate the proposed technique in terms of detection ratio, network scalability, power and intensity of the received signal. We assess the efficiency of the proposed detection method by considering an oil leak at different ocean levels. Finally, we propose a cooperative localization algorithm for localizing the leak in the UWSN. We then evaluate the proposed localization algorithm for two different topologies. Our results show that our proposed technique works well for an underwater network with concentric hexagonal topology. We can extend the proposed method for other types of targets with different shapes and sizes