IEEE802.15-14-0110-01-0mag MAC Timing Discussion Points for IEEE 802.15.4 Revision

Initial discussion document submitted by Benjamin A. Rolfe from Blind Creek Associates addressing MAC timing issues in the IEEE 802.15.4 standard revision. The document identifies potential problems, provides a list of questions for consideration, and outlines areas for improvement. It includes status updates, search methods for controlling MAC timing, and acknowledgment of complex issues in the Red Zone section.

• IEEE802.15
• MAC timing
• IEEE 802.15.4
• Revision
• Issues

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1. January 2014 doc.: IEEE802.15-14-0110-01-0mag Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: MAC Timing related discussion points for of 802.15.4 Revision Date Submitted: 25 February 2014 Source: Benjamin A. Rolfe Company: Blind Creek Associates Address: PO Box 798 Los Gatos CA 95031 Voice: +1 408 332 0725, E-Mail: ben @ blindcreek.com Re: Discussion of Timing related parameters and issues Abstract: Initial list of questions for consideration in revision, identify the problems for group attention. Purpose: Progress towards suitable fixes Notice: This document has been prepared to assist the IEEE P802.15. 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 P802.15. Contribution Slide 1 Ben Rolfe, BCA

2. January 2014 doc.: IEEE802.15-14-0110-01-0mag Purpose Identify the potential timing issues so that We can figure out which we are going to fix Figure out which to leave alone Comment fixing Contribution Slide 2 Ben Rolfe, BCA

3. January 2014 doc.: IEEE802.15-14-0110-01-0mag Status Document in progress (15-14-0111-00-0mag) lists all the attributes and constants that specify or affect specification of MAC timing. Color coded table - what it is and where it came from Red means issue we probably can t ignore Yellow means may need attention Blue means minor issues (editorial or other obvious fixes) The facts extracted and summarized Help see potential problems Still awork in progress Guidance from the group what next? Contribution Slide 3 Ben Rolfe, BCA

4. January 2014 doc.: IEEE802.15-14-0110-01-0mag Method Search standard for PIB attributes, constants and SAP parameters that may control or affect MAC timing 802.15.4-2011 802.15.4e-2012 802.15.4f-2012 802.15.4g-2012 802.15.4j-2013. 802.15.4k-2013 Draft P802.15.4m Draft P802-15-4p Examine definition and use of each Look for complex entanglements (dependencies or complex specs) Look for changes in amendments which may lead to conflicts Consider history what s been confused and debated Non-trivial task Contribution Slide 4 Ben Rolfe, BCA

5. January 2014 doc.: IEEE802.15-14-0110-01-0mag Red Zone 1. Acknowledgement Timing a) Complex, PHY specific definitions, some with mixed units b) Depends on a number of constants and other attributes that have been touched a lot c) Specified in more than one way and place in the standard d) Reference point for timers unclear e) When/if to use CSMA a) More than 4 different CSMA scenarios need addressing LIFs and SIFs a) Suggestion to replace with single IFS specification b) Ripples a lot (including into Ack timing) c) Backwards compatibility issues? d) Threshold for SIFS aTurnaroundTime a) Entangled in a lot of things 2. 3. Contribution Slide 5 Ben Rolfe, BCA

6. January 2014 doc.: IEEE802.15-14-0110-01-0mag Yellow Zone 1. macResponseWaitTime a) Complex definition dependent on attributes and constants that have changed throughout amendments b) Should review to ensure still valid for all PHYs macMaxFrameTotalWaitTime a) Complex definition dependent on a bunch of things b) Set by higher layer but specified like a read-only parameter aBaseSlotDuration and aBaseSuperframeDuration a) Used a lot of places, needs review aUnitBackoffPeriod and aCCATime a) Used in a number of places where it is maybe should not be; b) PHY specific but maybe should not be; c) Differing styles in amendments d) aUnitBackoffPeriod not changed by PHY amendments but maybe should have been? macEnhAckWaitDuration a) Needs precise definition of timing reference for transmission time (measured from what to where?) macMinLIFSPeriod and macMinSIFSPeriod\ a) Used but not defined (4e) 2. 3. 4. 5. 6. Contribution Slide 6 Ben Rolfe, BCA

7. January 2014 doc.: IEEE802.15-14-0110-01-0mag Blue Zone PHY dependent timings (6.4.3): some things stated as UWB PHY dependent are really ALOHA dependent macSyncSymbolOffset needs clean-up Duty cycle control macTxControlActiveDuration, macTxControlPauseDuration and macTxTotalDuration Intended to provide control of transmit duty cycle Specification confusion (no MAC or PHY function uses them) CCA Timing w/CCA Mode 4 Wait phyCCADuration/aCCATime and return clear or just return clear? Contribution Slide 7 Ben Rolfe, BCA

8. January 2014 doc.: IEEE802.15-14-0110-01-0mag Next Steps TBD Contribution Slide 8 Ben Rolfe, BCA