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Sunday, September 16, 2012

Which Wireless Technology for Industrial Sensor Network? The Development of OCARI Technology


Khaldoun Al Agha, Marc-Henry Bertin, Tuan Dang, Alexandre Guitton, Pascale Minet, Thietry Vsl, Jean-Baptiste Viollet
IEEE Transactions on Industrial Electronics, Vol.56.NO 10, October 2009

Summary
  The paper is issuing the importance of wireless technology in industrial applications, with a good introduction of what is the actual situation and problems in obtaining well enough performances.
When setting up an industrial wireless network, there are principally three aspect which must be paid certain attention: the physical and Media Access Control layers (PHY and MAC),the network layer and the application layer (APL).
In the first case considered as necessary are: robust radio transmission, low power consumption, compatibility with electromagnetic constraints, deterministic MACs.
In the second case considered are: network topology flexibility, network scalability, transparency for application layer (APL), energy aware routing protocol, support mobility, support anti-intrusion.
For the last case required are: support for application layers, support for application communication modes, support for electronic device description language for diagnosis and maintenance and support for authentication techniques. At the moment there are several options for wireless networks for industrial applications, all of them are based on IEEE 802.15.4, which still doesn’t keep into account an algorithm for power consumption control. The paper proposes OCARI (Optimization of Communication for Ad hoc Reliable Industrial networks) project, in which satisfies several physical layers, such as deterministic MAC layer for time-constrained communication, optimized energy-consumption routing strategy for increasing network’s life time and support of human walking-speed mobility.
The OCARI network topology is characterize by an industrial facility backbone to which a the workshop is coordinated (providing direct connection to the rest of the factory and internet connection as well); inside the workshop there are different cells, each with its cell coordinator (using a star topology).
For more information the reader can refer to the paper itself, what is important and has to underlined it the importance paid for energy consumption.
Since at the end point of the network there are devices carrying batteries, a strict relation with the battery life is carried on, devices should be kept asleep when they are not sending signals and should wake up on time when ready to receive signals.
Energy efficiency is obtained therefore with topology control algorithms, algorithms for reducing information transferred, energy efficient routing problem and scheduling node activity algorithms.
The first version of OCARI in 2009 still uses all nodes transmitting at maximum power, using or a neighborhood discovery and a topology dissemination.
Key Concepts
Wireless Networks for Industrial Applications
Key Results
In the overall OCARI seems to be a well enough system, integrating all the systems at the moment on hand, still some further improvement can be done in energy consumption.
It has been a technology which took everything that was at the moment on hand and integrated there pros, making is a successful network, still the paper hasn’t discussed about environment issue in the factory.

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