376 research outputs found
Alternate marking-based network telemetry for industrial WSNs
For continuous, persistent and problem-free operation of Industrial Wireless Sensor Networks (IWSN), it is critical to have visibility and awareness into what is happening on the network at any one time. Especially, for the use cases with strong needs for deterministic and real-time network services with latency and reliability guarantees, it is vital to monitor network devices continuously to guarantee their functioning, detect and isolate relevant problems and verify if all system requirements are being met simultaneously. In this context, this article investigates a light-weight telemetry solution for IWSNs, which enables the collection of accurate and continuous flowbased telemetry information, while adding no overhead on the monitored packets. The proposed monitoring solution adopts the recent Alternate Marking Performance Monitoring (AMPM) concept and mainly targets measuring end-to-end and hopby-hop reliability and delay performance in critical application flows. Besides, the technical capabilities and characteristics of the proposed solution are evaluated via a real-life implementation and practical experiments, validating its suitability for IWSNs
DTLS Performance in Duty-Cycled Networks
The Datagram Transport Layer Security (DTLS) protocol is the IETF standard
for securing the Internet of Things. The Constrained Application Protocol,
ZigBee IP, and Lightweight Machine-to-Machine (LWM2M) mandate its use for
securing application traffic. There has been much debate in both the
standardization and research communities on the applicability of DTLS to
constrained environments. The main concerns are the communication overhead and
latency of the DTLS handshake, and the memory footprint of a DTLS
implementation. This paper provides a thorough performance evaluation of DTLS
in different duty-cycled networks through real-world experimentation, emulation
and analysis. In particular, we measure the duration of the DTLS handshake when
using three duty cycling link-layer protocols: preamble-sampling, the IEEE
802.15.4 beacon-enabled mode and the IEEE 802.15.4e Time Slotted Channel
Hopping mode. The reported results demonstrate surprisingly poor performance of
DTLS in radio duty-cycled networks. Because a DTLS client and a server exchange
more than 10 signaling packets, the DTLS handshake takes between a handful of
seconds and several tens of seconds, with similar results for different duty
cycling protocols. Moreover, because of their limited memory, typical
constrained nodes can only maintain 3-5 simultaneous DTLS sessions, which
highlights the need for using DTLS parsimoniously.Comment: International Symposium on Personal, Indoor and Mobile Radio
Communications (PIMRC - 2015), IEEE, IEEE, 2015,
http://pimrc2015.eee.hku.hk/index.htm
An Analytical Model for Wireless Mesh Networks with Collision-Free TDMA and Finite Queues
Wireless mesh networks are a promising technology for connecting sensors and
actuators with high flexibility and low investment costs. In industrial
applications, however, reliability is essential. Therefore, two time-slotted
medium access methods, DSME and TSCH, were added to the IEEE 802.15.4 standard.
They allow collision-free communication in multi-hop networks and provide
channel hopping for mitigating external interferences. The slot schedule used
in these networks is of high importance for the network performance. This paper
supports the development of efficient schedules by providing an analytical
model for the assessment of such schedules, focused on TSCH. A Markov chain
model for the finite queue on every node is introduced that takes the slot
distribution into account. The models of all nodes are interconnected to
calculate network metrics such as packet delivery ratio, end-to-end delay and
throughput. An evaluation compares the model with a simulation of the Orchestra
schedule. The model is applied to Orchestra as well as to two simple
distributed scheduling algorithms to demonstrate the importance of
traffic-awareness for achieving high throughput.Comment: 17 pages, 14 figure
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
Towards efficient coexistence of IEEE 802.15.4e TSCH and IEEE 802.11
A major challenge in wide deployment of smart wireless devices, using
different technologies and sharing the same 2.4 GHz spectrum, is to achieve
coexistence across multiple technologies. The IEEE~802.11 (WLAN) and the IEEE
802.15.4e TSCH (WSN) where designed with different goals in mind and both play
important roles for respective applications. However, they cause mutual
interference and degraded performance while operating in the same space. To
improve this situation we propose an approach to enable a cooperative control
which type of network is transmitting at given time, frequency and place.
We recognize that TSCH based sensor network is expected to occupy only small
share of time, and that the nodes are by design tightly synchronized. We
develop mechanism enabling over-the-air synchronization of the Wi-Fi network to
the TSCH based sensor network. Finally, we show that Wi-Fi network can avoid
transmitting in the "collision periods". We provide full design and show
prototype implementation based on the Commercial off-the-shelf (COTS) devices.
Our solution does not require changes in any of the standards.Comment: 8 page
A Case for Time Slotted Channel Hopping for ICN in the IoT
Recent proposals to simplify the operation of the IoT include the use of
Information Centric Networking (ICN) paradigms. While this is promising,
several challenges remain. In this paper, our core contributions (a) leverage
ICN communication patterns to dynamically optimize the use of TSCH (Time
Slotted Channel Hopping), a wireless link layer technology increasingly popular
in the IoT, and (b) make IoT-style routing adaptive to names, resources, and
traffic patterns throughout the network--both without cross-layering. Through a
series of experiments on the FIT IoT-LAB interconnecting typical IoT hardware,
we find that our approach is fully robust against wireless interference, and
almost halves the energy consumed for transmission when compared to CSMA. Most
importantly, our adaptive scheduling prevents the time-slotted MAC layer from
sacrificing throughput and delay
Survey on wireless technology trade-offs for the industrial internet of things
Aside from vast deployment cost reduction, Industrial Wireless Sensor and Actuator Networks (IWSAN) introduce a new level of industrial connectivity. Wireless connection of sensors and actuators in industrial environments not only enables wireless monitoring and actuation, it also enables coordination of production stages, connecting mobile robots and autonomous transport vehicles, as well as localization and tracking of assets. All these opportunities already inspired the development of many wireless technologies in an effort to fully enable Industry 4.0. However, different technologies significantly differ in performance and capabilities, none being capable of supporting all industrial use cases. When designing a network solution, one must be aware of the capabilities and the trade-offs that prospective technologies have. This paper evaluates the technologies potentially suitable for IWSAN solutions covering an entire industrial site with limited infrastructure cost and discusses their trade-offs in an effort to provide information for choosing the most suitable technology for the use case of interest. The comparative discussion presented in this paper aims to enable engineers to choose the most suitable wireless technology for their specific IWSAN deployment
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