253 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
Evolving SDN for Low-Power IoT Networks
Software Defined Networking (SDN) offers a flexible and scalable architecture
that abstracts decision making away from individual devices and provides a
programmable network platform. However, implementing a centralized SDN
architecture within the constraints of a low-power wireless network faces
considerable challenges. Not only is controller traffic subject to jitter due
to unreliable links and network contention, but the overhead generated by SDN
can severely affect the performance of other traffic. This paper addresses the
challenge of bringing high-overhead SDN architecture to IEEE 802.15.4 networks.
We explore how traditional SDN needs to evolve in order to overcome the
constraints of low-power wireless networks, and discuss protocol and
architectural optimizations necessary to reduce SDN control overhead - the main
barrier to successful implementation. We argue that interoperability with the
existing protocol stack is necessary to provide a platform for controller
discovery and coexistence with legacy networks. We consequently introduce
{\mu}SDN, a lightweight SDN framework for Contiki, with both IPv6 and
underlying routing protocol interoperability, as well as optimizing a number of
elements within the SDN architecture to reduce control overhead to practical
levels. We evaluate {\mu}SDN in terms of latency, energy, and packet delivery.
Through this evaluation we show how the cost of SDN control overhead (both
bootstrapping and management) can be reduced to a point where comparable
performance and scalability is achieved against an IEEE 802.15.4-2012 RPL-based
network. Additionally, we demonstrate {\mu}SDN through simulation: providing a
use-case where the SDN configurability can be used to provide Quality of
Service (QoS) for critical network flows experiencing interference, and we
achieve considerable reductions in delay and jitter in comparison to a scenario
without SDN
Seamless roaming and guaranteed communication using a synchronized single-hop multi-gateway 802.15.4e TSCH network
Industrial wireless sensor networks (WSNs) are being used to improve the
efficiency, productivity and safety of industrial processes. An open standard
that is commonly used in such cases is IEEE 802.15.4e. Its TSCH mode employs a
time synchronized based MAC scheme together with channel hopping to alleviate
the impact of channel fading. Until now, most of the industrial WSNs have been
designed to only support static nodes and are not able to deal with mobility.
In this paper, we show how a single-hop, multi-gateway IEEE 802.15.4e TSCH
network architecture can tackle the mobility problem. We introduce the Virtual
Grand Master (VGM) concept that moves the synchronization point from separated
Backbone Border Routers (BBRs) towards the backbone network. With time
synchronization of all BBRs, mobile nodes can roam from one BBR to another
without time desynchronization. In addition to time synchronization, we
introduce a mechanism to synchronize the schedules between BBRs to support fast
handover of mobile nodes.Comment: Short paper version of a paper submitted to Ad-Hoc Networks Journal
by Elsevie
Hybrid schedule management in 6TiSCH networks : the coexistence of determinism and flexibility
With the emergence of the Internet of Things (IoT), Industry 4.0 and Cyber-Physical System (CPS) concepts, there is a tremendous change ongoing in industrial applications that is imposing increasingly diverse and demanding network dynamics and requirements with a wider and more fine-grained scale. The purpose of this article is to investigate how a Hybrid Schedule Management in 6TiSCH architecture can be used to achieve the coexistence of applications with heavily diverse networking requirements. We study the fundamental functionalities and also describe network scenarios where such a hybrid scheduling approach can be used. In addition, we present the details about the design and implementation of the first 6TiSCH Centralized Scheduling Framework based on CoMI. We also provide theoretical and experimental analysis where we study the cost of schedule management operations and illustrate the operation of the CoMI-based 6TiSCH Schedule Management
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
The analysis of energy consumption in 6TiSCH network nodes working in sub-GHz band
The 6TiSCH communication stack enables IPv6 networking over the TSCH (Time Slotted Channel Hopping) mode of operation defined in IEEE 802.15.4. Lately, it becomes an attractive solution for Low power and Lossy Networks (LLNs), suitable for Industrial Internet of Things (IIoT) applications. This article introduces a credible energy consumption model for the 6TiSCH network nodes, operating in the 863-870 MHz band. It presents the analysis leading to the construction of the model as well as detailed verification through experimental measurements which showed 98% accuracy in determining power consumption for two different network topologies. The article includes reliable battery lifetime predictions for transit and leaf nodes along with other parametric study results
Impact of EU duty cycle and transmission power limitations for sub-GHz LPWAN SRDs : an overview and future challenges
Long-range sub-GHz technologies such as LoRaWAN, SigFox, IEEE 802.15.4, and DASH7 are increasingly popular for academic research and daily life applications. However, especially in the European Union (EU), the use of their corresponding frequency bands are tightly regulated, since they must confirm to the short-range device (SRD) regulations. Regulations and standards for SRDs exist on various levels, from global to national, but are often a source of confusion. Not only are multiple institutes responsible for drafting legislation and regulations, depending on the type of document can these rules be informational or mandatory. Regulations also vary from region to region; for example, regulations in the United States of America (USA) rely on electrical field strength and harmonic strength, while EU regulations are based on duty cycle and maximum transmission power. A common misconception is the presence of a common 1% duty cycle, while in fact the duty cycle is frequency band-specific and can be loosened under certain circumstances. This paper clarifies the various regulations for the European region, the parties involved in drafting and enforcing regulation, and the impact on recent technologies such as SigFox, LoRaWAN, and DASH7. Furthermore, an overview is given of potential mitigation approaches to cope with the duty cycle constraints, as well as future research directions
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