Diego Dujovne

6TiSCH: deterministic IP-enabled industrial internet (of things)

Industrial and IP-enabled low-power wireless networking technologies are converging, resulting in the Industrial Internet of Things. On the one hand, low-power wireless solutions are available today that answer the strict reliability and power consumption requirements of industrial applications. These solutions are based on Time- Synchronized Channel Hopping, a medium access control technique at the heart of industrial standards such as the WirelessHART and ISA100.11a, and layer 1 and 2 standards such as IEEE802.15.4e. On the other hand, a range of standards have been published to allow low-power wireless devices to communicate using the Internet Protocol (IP), thereby becoming true “fingers of the Internet,” and greatly simplifying their integration into existing networks. This article acknowledges the standardization effort to combine those capabilities. The networks resulting from this convergence exhibit reliability and power consumption performances compatible with demanding industrial applications, while being easy to integrate, and following the end-to-end paradigm of todays Internet. In particular, this article presents the work being done in 6TiSCH, a newly-formed working group in the Internet Engineering Task Force, which is standardizing the mechanisms making the Industrial Internet of Things a reality.

On-the-Fly Bandwidth Reservation for 6TiSCH Wireless Industrial Networks

In smart factory applications, sensors, actuators, field devices, and supervision systems often require a high degree of reliability and timeliness in information exchange. The quality of service provided by the underlying industrial communication network is a key requisite for quality of control. In this context, the WirelessHART, ISA100.11a, and IEEE802.15.4e time-slotted channel hopping standards contribute novel protocols to support quasi-deterministic services, based on wireless short-range communication technologies. The recently created IETF 6TiSCH working group binds IPv6 to this market. Within the 6TiSCH architecture, the 6top sublayer manages the way communication resources are scheduled in time and frequency. The on-the-fly (OTF) bandwidth reservation module plays a complementary role; it is a distributed approach for adapting the scheduled bandwidth to network requirements. This paper first describes the OTF module and its interactions with the 6top sublayer. It then presents the simulation results of the OTF, drawn from a realistic 50-sensor mote multi-hop network that models a small industrial plant. Results show that the OTF can attain an end-to-end latency of the order of a second, with over 99% end-to-end reliability. The first real-world OTF implementation in OpenWSN is presented to demonstrate that it can easily be added within the 6TiSCH architecture.

A Taxonomy of IEEE 802.11 Wireless Parameters and Open Source Measurement Tools

The analysis and evaluation of new wireless network protocols is a long process that requires mathematical analysis, simulations, and increasingly experimentations under real conditions. Measurements are essential to analyze the performance of wireless protocols such as IEEE 802.11 networks in real environments, but experimentations are complex to perform and analyze. Usually, network researchers develop their own tools, sometimes from scratch, to fit the requirements of their experimentations, and these tools are then abandoned when the paper is published. In this study, we emphasize the importance, for the network research community, to use and contribute to the development of open source measurement tools. In this regard, we propose a survey and classification of IEEE 802.11 wireless parameters and open source tools available to collect or estimate these parameters. We highlight the parameters that can be extracted from wireless traffic probes and those that are available through the driver of wireless cards. Then, we introduce and compare open source tools that can be used to make the measurements, with special attention to the flexibility of the tools and their application scope. Finally, we discuss with several case studies the combination of tools that best suit the needs of the wireless experiments and provide a list of common pitfalls to avoid.

Guidelines for the Accurate Design of Empirical Studies in Wireless Networks

Traditionally, wireless protocol proposals have been often tested and validated using only analytical and simulation models. However, as the wireless environment is very complex to model accurately, and since the cost of wireless cards has decreased in an exponential way, today more and more research papers include evaluation of new proposals using experimentation on real devices. Indeed, experimentation is a mandatory step before possible deployment of new network protocols with real users. However, wireless experimentation is much more complex to set up and run than simulation, and it is important to avoid many pitfalls that can occur during experimentation. The objectives of this paper are twofold. First, we describe typical problems currently encountered in wireless-based experimentation, and we present simple guidelines to avoid them. Second, we propose an experimental methodology where the detection of anomalies, calibration of the measurement setup, and clear definition of the scenario (among others) make easier the repeatability of results. Finally, we showcase an implementation of the proposed methodology with an experimentation scenario whose objective is to analyze the stability of the wireless channel.

PcapWT: An efficient packet extraction tool for large volume network traces

Network packet tracing has been used for many different purposes during the last few decades, such as network software debugging, networking performance analysis, forensic investigation, and so on. Meanwhile, the size of packet traces becomes larger, as the speed of network rapidly increases. Thus, to handle huge amounts of traces, we need not only more hardware resources, but also e fficient software tools. However, traditional tools are inefficient at dealing with such big packet traces. In this paper, we propose pcapWT, an efficient packet extraction tool for large traces. PcapWT provides fast packet lookup by indexing an original trace using a Wavelet Tree structure. In addition, pcapWT supports multi-threading for avoiding synchronous I/O and blocking system calls used for file processing, and is particularly efficient on machines with SSD. PcapWT shows remarkable performance enhancements in comparison with traditional tools such as tcpdump and most recent tools such as pcapIndex in terms of index data size and packet extraction time. Our benchmark using large and complex traces shows that pcapWT reduces the index data size down below 1% of the volume of the original traces. Moreover, packet extraction performance is 20% better than with pcapIndex. Furthermore, when a small amount of packets are retrieved, pcapWT is hundreds of times faster than tcpdump.

GNUradio and 802.11: performance evaluation and limitations

In the last few years, software defined radio has become a widespread tool for research and development in the wireless arena. One of the drivers of this success is GnuRadio, an open source collection of signal processing routines, together with the inception of commercially available software radio front-ends to complete the signal chain. A number of wireless protocols have been developed on top of Gnu- Radio, including the ubiquitous 802.11 standard. In this article, we focus on the use and performance evaluation of the 802.11 BBN software-based transmitter and receiver implementation, highlighting its capabilities and limitations. In order to achieve this, we analyze the BER and packet error rate measurements on a reference scenario.

(Not so) intuitive results from a smart agriculture low-power wireless mesh deployment

A 21-node low-power wireless mesh network is deployed in a peach orchard. The network serves as a frost event prediction system. On top of sensor values, devices also report network statistics. In 3 months of operations, the network has produced over 4 million temperature values, and over 350,000 network statistics. This paper presents an in-depth analysis of the statistics, in order to precisely understand the performance of the network. Nodes in the network exhibit an expected lifetime between 4 and 16 years, with an end-to-end reliability of 100%. We show how -- contrary to popular belief -- wireless links are symmetric. Thanks to the use of Time Slotted Channel Hopping (TSCH), the network topology is very stable, with ≤5 link changes per day in the entire network.

A queue-based scheduling algorithm for PCE-enabled Industrial Internet of Things networks

The rise of the Industrial Internet of Things as a new paradigm for instrumentation and control has brought the use of internet-enabled constrained devices to complement and replace standard wired networks with wireless connectivity reducing deployment and maintenance costs. This work has been supported by the development of several industry standards, such as ISA100.11a, WirelessHART, 802.15.4e and the current 6TiSCH WG, to enable IPV6 for Time-Scheduled Channel Hopping (TSCH) networks. The most relevant features of TSCH networks are the intrinsic robustness and predictable delay, given a predefined schedule. In this paper, we propose a PCE-enabled scheduling approach to distribute cells within the slotframe by queueing the cell requirements derived from a number of different RPL DODAGs.

Characterization of LQI behavior in WSN for glacier area in Patagonia Argentina

One of the most important aspects before installing a Wireless Sensor Network (WSN) is a previous study of connectivity constraints that exist in the area to be covered. This study is critical to the final distribution of the sensors, with an important impact in the life of the network by reducing consumption, and on the robustness by contemplating redundancy of paths and sensors. In this paper, we present a summary of the most important aspects of a preliminary empirical study of the Link Quality Indicator (LQI), on different landscapes in the glaciers area of Patagonia Argentina. The landscapes covered varied in geographical structures with different levels of attenuation and extreme environmental conditions. Through the analysis of the Cumulative Distribution Function (CDF) of the measured LQI values, we can characterize the behavior of four different scenarios and correlate the combined effects of the environmental structure with the distance from the transmitter. The measurements performed were designed for characterizing the links at the physical layer with the purpose of defining models to estimate the Packet Error Rate (PER) for the WSN deployment stage.

A Demo of the PEACH IoT-Based Frost Event Prediction System for Precision Agriculture

In 2013, 85% of the peach production in the Mendoza region (Argentina) was lost because of frost. In a couple of hours, farmers can lose everything. Handling a frost event is possible, but it is hard to predict when it is going to happen. The goal of the PEACH project is to predict frost events by analyzing measurements from sensors deployed around an orchard. This demo provides an overview of the complete solution we designed and deployed: the low-power wireless network and the back-end system. The low-power wireless network is composed entirely of commercial off-the-shelf devices. We develop a methodology for deploying the network and present the open-source tools to assist with the deployment, and to monitor the network. The deployed low-power wireless mesh network, built around SmartMesh IP, is 100% reliable, with end-to-end latency below 2 s, and over 3 years of battery lifetime.