216 research outputs found
Using Existing Network Simulators for Power-Aware Self-Organizing Wireless Sensor Network Protocols
In this document, we compare three existing simulation platforms (OPNET
Modeler, Network Simulator 2, Georgia Tech Sensor Network Simulator). Our
comparative study focuses on ease of use, scalability, ease of implementing
power consumption model and physical layer modeling accuracy, mainly.
Conclusions of this study are presented, and will help us decide which
simulating environment to use for evaluating power-aware self-organizing sensor
networks protocols
Understanding the limits of LoRaWAN
The quick proliferation of LPWAN networks, being LoRaWAN one of the most
adopted, raised the interest of the industry, network operators and facilitated
the development of novel services based on large scale and simple network
structures. LoRaWAN brings the desired ubiquitous connectivity to enable most
of the outdoor IoT applications and its growth and quick adoption are real
proofs of that. Yet the technology has some limitations that need to be
understood in order to avoid over-use of the technology. In this article we aim
to provide an impartial overview of what are the limitations of such
technology, and in a comprehensive manner bring use case examples to show where
the limits are
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
Virtual reassembly buffers in 6LoWPAN - draft-ietf-lwig-6lowpan-virtual-reassembly-00
International audienc
Experimental Clock Calibration\\on a Crystal-Free Mote-on-a-Chip
The elimination of the off-chip frequency reference, typically a crystal
oscillator, would bring important benefits in terms of size, price and energy
efficiency to IEEE802.15.4 compliant radios and systems-on-chip. The stability
of on-chip oscillators is orders of magnitude worse than that of a crystal. It
is known that as the temperature changes, they can drift more than 50
ppm/{\deg}C. This paper presents the result of an extensive experimental study.
First, we propose mechanisms for crystal-free radios to be able to track an
IEEE802.15.4 join proxy, calibrate the on-chip oscillators and maintain
calibration against temperature changes. Then, we implement the resulting
algorithms on a crystal-free platform and present the results of an
experimental validation. We show that our approach is able to track a
crystal-based IEEE802.15.4-compliant join proxy and maintain the requested
radio frequency stability of +/-40 ppm, even when subject to temperature
variation of 2{\deg}C/min.Comment: CNERT: Computer and Networking Experimental Research using Testbeds,
in conjunction with IEEE INFOCOM 2019, April 29 - May 2, 2019, Paris, Franc
The Cost of Installing a 6TiSCH Schedule
International audienceScheduling in an IEEE802.15.4e TSCH (6TiSCH) low-power wireless mesh network can be done in a centralized or distributed way. When using centralized scheduling, a scheduler computes a communication schedule, which then needs to be installed into the network. This can be done using standards such CoAP and CoMI, or using a custom protocol such as OCARI. In this paper, we compute the number of messages installing and updating the schedule takes, using both approaches, on a realistic example scenario. The cost of using today's standards is high. In some cases, a standards-based solution requires approximately 4 times more messages to be transmitted in the network, than when using a custom protocol. This paper makes three simple recommended changes to the standards which, when integrated, reduce the cost of a standards based solution by 18% to 74%. Since they are still being developed, these recommendations can easily be integrated into the standards
WiFly: experimenting with Wireless Sensor Networks and Virtual coordinates
Experimentation is important when designing communication protocols for
Wireless Sensor Networks. Lower-layers have a major impact on upper-layer
performance, and the complexity of the phenomena can not be entirely captured
by analysis or simulation. In this report, we go through the complete process,
from designing an energy-efficient self-organizing communication architecture
(MAC, routing and application layers) to real-life experimentation roll-outs.
The presented communication architecture includes a MAC protocol which avoids
building and maintaining neighborhood tables, and a geographically-inspired
routing protocol over virtual coordinates. The application consists of a mobile
sink interrogating a wireless sensor network based on the requests issued by a
disconnected base station. After the design process of this architecture, we
verify it functions correctly by simulation, and we perform a temporal
verification. This study is needed to calculate the maximum speed the mobile
sink can take. We detail the implementation, and the results of the off-site
experimentation (energy consumption at PHY layer, collision probability at MAC
layer, and routing). Finally, we report on the real-world deployment where we
have mounted the mobile sink node on a radio-controlled airplane
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