An isochronous medium access for real-time wireless communications in industrial automation systems - A use case for wireless clock synchronization

Wireless technologies are increasingly deployed in factory automation systems, because they are able to provide several advantages, e. g., a higher level of mobility, more flexibility, and at the same time causing lower costs. However, the requirements of industrial applications in terms of real-time communication can not be satisfied by existing wireless technologies, such as IEEE 802.11Wireless Local Area Networks (WLANs). This is due to their unpredictable behaviour and the introduction of delays beyond acceptable bounds, mainly caused by a non-deterministic medium access. Hence, the proposed wireless communication system provides real-time communication services based on the IEEE 802.11 protocol family. In this paper we present a new isochronous medium access control mechanism, called IsoMAC. The paper addresses IsoMAC and shows how, in combination with a suitable wireless clock synchronization, IsoMAC is able to satisfy the typical constraints of soft real-time flows found on the factory floor. A simulation case study is provided that shows the achievable update times of the proposed combination.

[1]  Peter Martini,et al.  Graph based Metrics for Intrusion Response Measures in Computer Networks , 2007 .

[2]  A. Varga,et al.  Using the OMNeT++ discrete event simulation system in education , 1999 .

[3]  Andreas Willig.  A MAC protocol and a scheduling approach as elements of a lower layers architecture in wireless industrial LANs , 1997, Proceedings 1997 IEEE International Workshop on Factory Communication Systems. WFCS'97.

[4]  Ricardo Moraes,et al.  Real-Time Communication in IEEE 802.11 Networks: Timing Analysis and a Ring Management Scheme for the VTP-CSMA Architecture , 2007 .

[5]  Henning Trsek,et al.  A Simulation Case Study of the new IEEE 802.11e HCCA mechanism in Industrial Wireless Networks , 2006, 2006 IEEE Conference on Emerging Technologies and Factory Automation.

[6]  Timo Hämäläinen,et al.  Software and hardware prototypes of the IEEE 1588 precision time protocol on wireless LAN , 2005, 2005 14th IEEE Workshop on Local & Metropolitan Area Networks.

[7]  Theodore S. Rappaport,et al.  Propagation measurements and models for wireless communications channels , 1995, IEEE Commun. Mag..

[8]  Edgar Nett,et al.  Clock synchronization for wireless local area networks , 2000, Proceedings 12th Euromicro Conference on Real-Time Systems. Euromicro RTS 2000.

[9]  L. Seno,et al.  Analysis of Ethernet Powerlink Wireless Extensions Based on the IEEE 802.11 WLAN , 2009, IEEE Transactions on Industrial Informatics.

[10]  Sin-Chong Park,et al.  An effective polling MAC scheme for IEEE 802.11e , 2004, IEEE International Symposium on Communications and Information Technology, 2004. ISCIT 2004..

[11]  Andreas Willig,et al.  Wireless Technology in Industrial Networks , 2005, Proceedings of the IEEE.

[12]  Giorgio C. Buttazzo,et al.  FTT-Ethernet: a flexible real-time communication protocol that supports dynamic QoS management on Ethernet-based systems , 2005, IEEE Transactions on Industrial Informatics.

[13]  Henning Trsek,et al.  Towards high accuracy in IEEE 802.11 based clock synchronization using PTP , 2011, 2011 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control and Communication.

[14]  Lucia Lo Bello,et al.  A traffic scheduler for real-time wireless communication in adaptable industrial automation systems , 2010, 2010 IEEE 15th Conference on Emerging Technologies & Factory Automation (ETFA 2010).

[15]  Eduardo Tovar,et al.  Real-time communications over hybrid wired/wireless PROFIBUS-based networks , 2002, Proceedings 14th Euromicro Conference on Real-Time Systems. Euromicro RTS 2002.

[16]  Todor Cooklev,et al.  An Implementation of IEEE 1588 Over IEEE 802.11b for Synchronization of Wireless Local Area Network Nodes , 2007, IEEE Transactions on Instrumentation and Measurement.

[17]  Gianluca Cena,et al.  Hybrid wired/wireless networks for real-time communications , 2008, IEEE Industrial Electronics Magazine.

[18]  Andreas Willig,et al.  Measurements of a wireless link in an industrial environment using an IEEE 802.11-compliant physical layer , 2002, IEEE Trans. Ind. Electron..

[19]  Kang Lee,et al.  IEEE 1588 standard for a precision clock synchronization protocol for networked measurement and control systems , 2002, 2nd ISA/IEEE Sensors for Industry Conference,.

[20]  Gianluca Cena,et al.  On the Performance of IEEE 802.11e Wireless Infrastructures for Soft-Real-Time Industrial Applications , 2010, IEEE Transactions on Industrial Informatics.

[21]  Sunghyun Choi,et al.  Wireless LAN for Quality of Service , 2001 .

[22]  José Alberto Fonseca,et al.  VTP-CSMA: A Virtual Token Passing Approach for Real-Time Communication in IEEE 802.11 Wireless Networks , 2007, IEEE Transactions on Industrial Informatics.