doc.: IEEE r0 Submission July 2008 L. Winkel, M. Bahr, Siemens AGSlide 1 Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [ Preliminary Proposal for Factory Automation ] Date Submitted: [ 15 July, 2008 ] Source: [ Ludwig Winkel, Michael Bahr ] Company [ Siemens AG ] Address [Siemensallee 74, Karlsruhe, Germany] Voice:[ ], FAX: [ ], Re: [response to Call for Preliminary Proposals doc 15-08/0373r1] Abstract:[Preliminary proposal to IEEE e for wireless sensor/actuator networks applicable for factory automation.] Purpose:[amending for matching the requirements for factory automation] Notice:This document has been prepared to assist the IEEE P It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release:The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P

doc.: IEEE r0 Submission July 2008 L. Winkel, M. Bahr, Siemens AGSlide 2 Preliminary Proposal for Factory Automation Ludwig Winkel (Siemens AG) Michael Bahr (Siemens AG)

doc.: IEEE r0 Submission July 2008 L. Winkel, M. Bahr, Siemens AGSlide 3 Overview Support of factory automation and process automation Proposal for Factory Automation –Motivation –Proposed MAC solution Considerations for Process Automation –Mesh Support

doc.: IEEE r0 Submission July 2008 L. Winkel, M. Bahr, Siemens AGSlide 4 Support of Process Automation and Factory Automation process automation (PA) and factory automation (FA) are related but quite inde- pendent use cases with different requirements use of same wireless communication technology (IEEE ) is beneficial configurability of IEEE e –common base functionality –configurable for process automation use cases –configurable for factory automation use cases

doc.: IEEE r0 Submission July 2008 L. Winkel, M. Bahr, Siemens AGSlide 5 MAC Proposal for Factory Automation

doc.: IEEE r0 Submission July 2008 L. Winkel, M. Bahr, Siemens AGSlide 6 Use Cases of Factory Automation automotive – robots – suspension tracks – portable machine tools –milling, turning –robot revolver filling cargo – airport logistics – post packaging industry special engineering conveyor technique

doc.: IEEE r0 Submission July 2008 L. Winkel, M. Bahr, Siemens AGSlide 7 Requirements and Assumptions high determinism high reliability low latency: –transmission of sensor data in  10 ms –low round-trip time many sensors per gateway –might be more than 100 sensors per gateway assume controlled envi- ronment (factory floor) configuration for optimal performance network management and frequency planning for avoidance of co- existence issues

doc.: IEEE r0 Submission July 2008 L. Winkel, M. Bahr, Siemens AGSlide 8 Why IEEE ? coexistence with IEEE WLAN –3 non-overlapping channels for IEEE –4 channels for IEEE sufficient range worldwide acceptance worldwide standard North America (similar worldwide)

doc.: IEEE r0 Submission July 2008 L. Winkel, M. Bahr, Siemens AGSlide 9 Network Topology star topology gateway devices –sensors: unidirectional data exchange from devices to gateway –actuators: bidirectional data exchange between devices and gateway

doc.: IEEE r0 Submission July 2008 L. Winkel, M. Bahr, Siemens AGSlide 10 General Concept IEEE PHY frames Time Division Multiple Access –Superframe with timeslots of fixed length –shared group timeslots with CSMA –addressing based on timeslot location or short address –modified MAC frame no channel hopping

doc.: IEEE r0 Submission July 2008 L. Winkel, M. Bahr, Siemens AGSlide 11 PHY Frame Format IEEE PHY frame format different preamble values –differentiate IEEE e FA devices from other IEEE devices

doc.: IEEE r0 Submission July 2008 L. Winkel, M. Bahr, Siemens AGSlide 12 Time Division Multiple Access Superframe –starts with beacon –followed by n timeslots of equal, fixed length Timeslots –one device per timeslot (dedicated timeslot) –determinism (re-)synchronization through beacon –allows sleep mode / power save of devices time slot time

doc.: IEEE r0 Submission July 2008 L. Winkel, M. Bahr, Siemens AGSlide 13 Shared Group Timeslots more than one device per timeslot carrier sense multiple access within shared group timeslot 1 or more continous timeslots concatenated to a shared group timeslot all timeslots in single shared group timeslot  network with carrier sense multiple access mixture between fixed, deterministic timeslots and shared group timeslots possible time slot time

doc.: IEEE r0 Submission July 2008 L. Winkel, M. Bahr, Siemens AGSlide 14 Structure of Superframe existence of management timeslots configurable during setup number of (timeslots for) sensors and actuators configurable during setup sensors time actuators

doc.: IEEE r0 Submission July 2008 L. Winkel, M. Bahr, Siemens AGSlide 15 MAC Frame Format implicit addressing through slot number –omits MAC header fields very short PSDU increases efficiency dramatically –turnaround time / latency main criteria –every bit counts: data payload is very short assume 2 byte data payload 3 more bytes mean a 30% increase in latency! FCS for error recognition

doc.: IEEE r0 Submission July 2008 L. Winkel, M. Bahr, Siemens AGSlide 16 Transmission Modes 3 transmission modes –Discovery –Configuration –Online transmission mode is signalled in beacon

doc.: IEEE r0 Submission July 2008 L. Winkel, M. Bahr, Siemens AGSlide 17 Discovery Mode first step in network setup (addition of new devices) device sends its current configuration to gateway till ACK

doc.: IEEE r0 Submission July 2008 L. Winkel, M. Bahr, Siemens AGSlide 18 Configuration Mode second step in network setup used for re-configuration of network gateway sends new configuration to device

doc.: IEEE r0 Submission July 2008 L. Winkel, M. Bahr, Siemens AGSlide 19 Configurable Parameters structure of superframe (management timeslots, sensor timeslots, actuator timeslots) number of timeslots duration of timeslots shared group timeslots transmission channel

doc.: IEEE r0 Submission July 2008 L. Winkel, M. Bahr, Siemens AGSlide 20 Online Mode transmission of the actual data for factory automation (productivity data) gateway acknowledges receipt of data from sensors in beacon gateway signals direction of transmission for actuator timeslots in beacon –transmission with or without acknowledgement or with block acknowledgement

doc.: IEEE r0 Submission July 2008 L. Winkel, M. Bahr, Siemens AGSlide 21 Use of Single Channel avoids „unproductive“ channel switch times allows addressing by timeslot better support of roaming (e.g. conveyor belts) very good coexistence with other wireless networks (e.g. WLAN on different channels)

doc.: IEEE r0 Submission July 2008 L. Winkel, M. Bahr, Siemens AGSlide 22 Considerations on Process Automation see also 15-08/409r2

doc.: IEEE r0 Submission July 2008 L. Winkel, M. Bahr, Siemens AGSlide 23 Mesh Support applicable for process automation IEEE header extensions for mesh support –additional addresses (source, destination) –sequence number –TTL („transmissions to live“) framework for chosing path selection mechanisms –path selection protocol –link metrics

doc.: IEEE r0 Submission July 2008 L. Winkel, M. Bahr, Siemens AGSlide 24 Frame Forwarding received frames for other nodes are forwarded to the next hop according to aquired forwarding information frame forwarding capability required, realization implementation specific

doc.: IEEE r0 Submission July 2008 L. Winkel, M. Bahr, Siemens AGSlide 25 Summary configurable distinction between factory automation and process automation propose highly efficient TDMA-based MAC scheme for factory automation –IEEE PHY –very short latency through short data packets in short dedicated timeslots of fixed length –shared group timeslots –configurability mesh support for process automation