Low Power, Low Delay: Opportunistic Routing meets Duty Cycling

Traditionally, routing in wireless sensor networks consists of two steps: First, the routing protocol selects a next hop, and, second, the MAC protocol waits for the intended destination to wake up and receive the data. This design makes it difficult to adapt to link dynamics and introduces delays while waiting for the next hop to wake up. In this paper we introduce ORW, a practical opportunistic routing scheme for wireless sensor networks. In a dutycycled setting, packets are addressed to sets of potential receivers and forwarded by the neighbor that wakes up first and successfully receives the packet. This reduces delay and energy consumption by utilizing all neighbors as potential forwarders. Furthermore, this increases resilience to wireless link dynamics by exploiting spatial diversity. Our results show that ORW reduces radio duty-cycles on average by 50% (up to 90% on individual nodes) and delays by 30% to 90% when compared to the state of the art

A critical analysis of research potential, challenges and future directives in industrial wireless sensor networks

In recent years, Industrial Wireless Sensor Networks (IWSNs) have emerged as an important research theme with applications spanning a wide range of industries including automation, monitoring, process control, feedback systems and automotive. Wide scope of IWSNs applications ranging from small production units, large oil and gas industries to nuclear fission control, enables a fast-paced research in this field. Though IWSNs offer advantages of low cost, flexibility, scalability, self-healing, easy deployment and reformation, yet they pose certain limitations on available potential and introduce challenges on multiple fronts due to their susceptibility to highly complex and uncertain industrial environments. In this paper a detailed discussion on design objectives, challenges and solutions, for IWSNs, are presented. A careful evaluation of industrial systems, deadlines and possible hazards in industrial atmosphere are discussed. The paper also presents a thorough review of the existing standards and industrial protocols and gives a critical evaluation of potential of these standards and protocols along with a detailed discussion on available hardware platforms, specific industrial energy harvesting techniques and their capabilities. The paper lists main service providers for IWSNs solutions and gives insight of future trends and research gaps in the field of IWSNs

Distributed Cyber-Physical Systems with Unmanned Aerial Vehicles

This thesis discusses the merger between Unmanned Aerial Vehicles (UAVs) and static wireless sensor networks (WSNs). It explores and demonstrates the use of UAVs as mobile sinks to collect data from static sensor networks. A communication protocol is developed to approach a 100% data reliability while trying to maximise the speed of the UAV. An energy model and speed versus reliability models are developed and tested using MATLAB. Mathematical models are developed to calculate the energy needed by nodes in such a system. The energy model developed is used to inform the design of recharging systems with wireless power transfer and consider energy harvesting opportunities. The protocol developed is an asynchronous communication protocol. It is devel- oped in ContikiOS on top of ContikiMAC radio duty cycling protocol using the Rime communication stack. A series of indoor and outdoor tests are conducted using real hardware and the performance of this protocol is compared with CTP. The results show that the protocol developed has 100% data reliability when the speed of the UAV is less than 12m/s. Based on the performance results obtained, subsequent numerical analysis shows that operational lifetime of nodes under these conditions can extend to 1.8 years using a typical 2400 mAH battery. This work is one of the rst practical demonstrations of UAVs with WSN and highlights a number of consequential research questions

Towards Energy Efficient, High-speed Communication in WSNs

Traditionally, protocols in wireless sensor networks focus on low-power operation with low data-rates. In addition, a small set of protocols provides high throughput communication. With sensor networks developing into general propose networks, we argue that protocols need to provide both: low data-rates at high energy-efficiency and, additionally, a high throughput mode. This is essential, for example, to quickly collect large amounts of raw-data from a sensor. This paper presents a set of practical extensions to the low-power, low delay routing protocol ORW. We introduce the capability to handle multiple, concurrent bulk-transfers in dynamic application scenarios. Overall, our extensions allow ORW to reach an almost 500% increase in the throughput with less than a 25% increase of the power consumption during a bulk transfer. Thus, we show that instead of developing a new protocol from scratch, we can carefully enhance an existing, energy-efficient protocol with high-throughput extensions. Both the energy-efficient low data-rate mode and the high throughput extensions transparently coexist inside a single protocol

Wireless industrial monitoring and control networks: the journey so far and the road ahead

While traditional wired communication technologies have played a crucial role in industrial monitoring and control networks over the past few decades, they are increasingly proving to be inadequate to meet the highly dynamic and stringent demands of today’s industrial applications, primarily due to the very rigid nature of wired infrastructures. Wireless technology, however, through its increased pervasiveness, has the potential to revolutionize the industry, not only by mitigating the problems faced by wired solutions, but also by introducing a completely new class of applications. While present day wireless technologies made some preliminary inroads in the monitoring domain, they still have severe limitations especially when real-time, reliable distributed control operations are concerned. This article provides the reader with an overview of existing wireless technologies commonly used in the monitoring and control industry. It highlights the pros and cons of each technology and assesses the degree to which each technology is able to meet the stringent demands of industrial monitoring and control networks. Additionally, it summarizes mechanisms proposed by academia, especially serving critical applications by addressing the real-time and reliability requirements of industrial process automation. The article also describes certain key research problems from the physical layer communication for sensor networks and the wireless networking perspective that have yet to be addressed to allow the successful use of wireless technologies in industrial monitoring and control networks

Hidden Terminal-Aware Contention Resolution with an Optimal Distribution

Achieving low-power operation in wireless sensor networks with high data load or bursty traffic is challenging. The hidden terminal problem is aggravated with increased amounts of data in which traditional backoff-based contention resolution mechanisms fail or induce high latency and energy costs. We analyze and optimize Strawman, a receiver-initiated contention resolution mechanism that copes with hidden terminals. We propose new techniques to boost the performance of Strawman while keeping the resolution overhead small. We finally validate our improved mechanism via experiments

Politecast - a new communication primitive for wireless sensor networks

Wireless sensor networks have the potential for becoming a huge market. Ericsson predicts 50 billion devices interconnected to the Internet by the year 2020. Before that, the devices must be made to be able to withstand years of usage without having to change power source as that would be too costly. These devices are typically small, inexpensive and severally resource constrained. Communication is mainly wireless, and the wireless transceiver on the node is typically the most power hungry component. Therefore, reducing the usage of radio is key to long lifetime. In this thesis I identify four problems with the conventional broadcast primitive. Based on those problems, I implement a new communication primitive. This primitive is called Politecast. I evaluate politecast in three case studies: the Steal the Light toy example, a Neighbor Discovery simulation and a full two-month deployment of the Lega system in the art gallery Liljevalchs. With the evaluations, Politecast is shown to be able to massively reduce the amount of traffic being transmitted and thus reducing congestion and increasing application performance. It also prolongs node lifetime by reducing the overhearing by waking up neighbors

Energy autonomous systems : future trends in devices, technology, and systems

The rapid evolution of electronic devices since the beginning of the nanoelectronics era has brought about exceptional computational power in an ever shrinking system footprint. This has enabled among others the wealth of nomadic battery powered wireless systems (smart phones, mp3 players, GPS, …) that society currently enjoys. Emerging integration technologies enabling even smaller volumes and the associated increased functional density may bring about a new revolution in systems targeting wearable healthcare, wellness, lifestyle and industrial monitoring applications