Arta Dilo

A virtual infrastructure based on honeycomb tessellation for data dissemination in multi-sink mobile wireless sensor networks

A new category of intelligent sensor network applications emerges where motion is a fundamental characteristic of the system under consideration. In such applications, sensors are attached to vehicles, or people that move around large geographic areas. For instance, in mission critical applications of wireless sensor networks (WSNs), sinks can be associated to first responders. In such scenarios, reliable data dissemination of events is very important, as well as the efficiency in handling the mobility of both sinks and event sources. For this kind of applications, reliability means real-time data delivery with a high data delivery ratio. In this article, we propose a virtual infrastructure and a data dissemination protocol exploiting this infrastructure, which considers dynamic conditions of multiple sinks and sources. The architecture consists of highways in a honeycomb tessellation, which are the three main diagonals of the honeycomb where the data flow is directed and event data is cached. The highways act as rendezvous regions of the events and queries. Our protocol, namely hexagonal cell-based data dissemination (HexDD), is fault-tolerant, meaning it can bypass routing holes created by imperfect conditions of wireless communication in the network. We analytically evaluate the communication cost and hot region traffic cost of HexDD and compare it with other approaches. Additionally, with extensive simulations, we evaluate the performance of HexDD in terms of data delivery ratio, latency, and energy consumption. We also analyze the hot spot zones of HexDD and other virtual infrastructure based protocols. To overcome the hot region problem in HexDD, we propose to resize the hot regions and evaluate the performance of this method. Simulation results show that our study significantly reduces overall energy consumption while maintaining comparably high data delivery ratio and low latency.

RoADS: A Road Pavement Monitoring System for Anomaly Detection Using Smart Phones

Monitoring the road pavement is a challenging task. Authorities spend time and finances to monitor the state and quality of the road pavement. This paper investigate road surface monitoring with smartphones equipped with GPS and inertial sensors: accelerometer and gyroscope. nIn this study we describe the conducted experiments with data from the time domain, frequency domain and wavelet transformation, and a method to reduce the effects of speed, slopes and drifts from sensor signals. A new audiovisual data labelling technique is proposed. Our system named RoADS, implements wavelet decomposition analysis for signal processing of inertial sensor signals and Support Vector Machine (SVM) for anomaly detection and classification. Using these methods we are able to build a real time multiclass road anomaly detector. We obtained a consistent accuracy of ≈90% on detecting severe anomalies regardless of vehicle type and road location. Local road authorities and communities can benefit from this system to evaluate the state of their road network pavement in real time.

Implementation of WirelessHART in NS-2 simulator

One of the first standards in the wireless sensor networks domain, WirelessHART, was introduced to address industrial process automation and control requirements. The standard can be used as a reference point to evaluate other wireless protocols in the domain of industrial monitoring and control. This makes it worthwhile to set up a reliable WirelessHART simulator to achieve that reference point in a relatively easy way. This paper explains our implementation of WirelessHART in the NS-2 simulator. According to our knowledge, this is the first implementation that supports the WirelessHART network manager as well as the whole stack of the WirelessHART standard. We evaluated the performance of our implementation in terms of delay and communication load in the network. This implementation offers an alternative to expensive testbeds for testing WirelessHART.

Optimization Problems in Wireless Sensor Networks

The Wireless Sensor Networks (WSNs) design related questions give rise to new complex and difficult theoretical problems and challenges in operations research and optimization areas. As WSNs become increasingly pervasive, a good understanding of these problems in terms of theoretical complexity is of great help in designing appropriate algorithms. In this paper, we examine some of the most fundamental optimization problems related to coverage, topology control, scheduling, routing and mobility in WSNs. Then we focus on their complexity and analyze the differences that exist with the counter part conventional theoretical problems or those already studied in traditional networks. We present as well some of the main methods proposed in the literature and report some open issues regarding these problems.

Review of Optimization Problems in Wireless Sensor Networks

Wireless Sensor Networks (WSNs) are an interesting field of research because of their numerous applications and the possibility of integrating them into more complex network systems. The difficulties encountered in WSN design usually relate either to their stringent constraints, which include energy, bandwidth, memory and computational capabilities, or to the requirements of the particular application. As WSN design problems become more and more challenging, advances in the areas of Operations Research (OR) and Optimization are becoming increasingly useful in addressing them.

D-MSR: a distributed network management scheme for real-time monitoring and process control applications in wireless industrial automation.

Current wireless technologies for industrial applications, such as WirelessHART and ISA100.11a, use a centralized management approach where a central network manager handles the requirements of the static network. However, such a centralized approach has several drawbacks. For example, it cannot cope with dynamicity/disturbance in large-scale networks in a real-time manner and it incurs a high communication overhead and latency for exchanging management traffic. In this paper, we therefore propose a distributed network management scheme, D-MSR. It enables the network devices to join the network, schedule their communications, establish end-to-end connections by reserving the communication resources for addressing real-time requirements, and cope with network dynamicity (e.g., node/edge failures) in a distributed manner. According to our knowledge, this is the first distributed management scheme based on IEEE 802.15.4e standard, which guides the nodes in different phases from joining until publishing their sensor data in the network. We demonstrate via simulation that D-MSR can address real-time and reliable communication as well as the high throughput requirements of industrial automation wireless networks, while also achieving higher efficiency in network management than WirelessHART, in terms of delay and overhead.

Intelligent Systems for Crisis Management

There have been major advances in technologies to support crisis response in the last few years. However, many aspects related to the efficient collection and integration of geo-information, applied semantics and situation awareness for disaster management are still open. To advance the systems and make them intelligent, an extensive collaboration is required between emergency responders, disaster managers, system designers and researchers. nThis book contains a selection of 19 scientific and 10 best-practice peer-reviewed papers.

Geo-casting of queries combined with coverage area reporting for wireless sensor networks

In order to efficiently deal with queries or other location dependent information, it is key that the wireless sensor network informs gateways what geographical area is serviced by which gateway. The gateways are then able to e.g. efficiently route queries which are only valid in particular regions of the deployment. The proposed algorithms combine coverage area reporting and geographical routing of queries which are injected by gateways. The combined solution is evaluated in terms of computational complexity and performance compared with existing geocasting protocols.

A fault-tolerant data dissemination based on Honeycomb Architecture for Mobile Multi-Sink wireless sensor networks

In mission critical applications of wireless sensor networks (WSNs), multiple sinks can be associated to first responders such as firefighters, but also to unmanned aerial vehicles (UAVs). In such scenarios, data dissemination of events towards mobile sinks should be performed reliably. In this paper we present Honeycomb Architecture which enables data dissemination considering dynamic conditions of multiple sinks and sources. Honeycomb Architecture exploits a virtual infrastructure called ‘highways’, which is an area where all event data are cached. The ‘highways’ act as rendezvous regions of the events and queries. Once a query is issued, it is sent to one of the ‘highways’ and searches relevant data stored in the ‘highway’. When the data is found, it is sent to the sink which has issued the query. Our data dissemination protocol is fault-tolerant, i.e., it can bypass holes in the network. We evaluate and compare the data delivery ratio and latency of our data dissemination protocol with previous approaches. We also analyze the hotspot regions in the network with different protocols. Simulation results show that our work significantly reduces overall energy consumption while maintaining comparably high data delivery ratio.

ISA100.11a*: The ISA100.11a extension for supporting energy-harvested I/O devices

Wireless standards developed for industrial applications such as ISA100.11a and WirelessHART, generally use centralized management approaches. However, such centralized approaches cannot cope with network dynamicity in real-time manner. They also incur high management overhead and latency. Consequently, the network becomes unsuitable for resource constraint devices, e.g I/O devices. The problems become exacerbated when the network scales up. ISA100.11a standard allows reduced functionality devices in the network and supports hybrid network topology. We propose an extension to ISA100.11a to better address the requirements of the energy constrained I/O devices. The proposed extension makes the management more decentralized by delegating a part of the management responsibility to the routers in the network. It also allows the I/O devices to choose their best routers according to the metric considered using local statistics and advertised routers ranks. We show that the proposed extension can better address the realtime and reliability requirements of industrial wireless networks. It can achieve higher network management efficiency in terms of reducing the delay and overhead of I/O devices than the ISA100.11a standard.