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Contribution doc.: IEEE802.15-14-0110-01-0mag January 2014 Slide 1 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. Ben Rolfe, BCA
Contribution 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 January 2014 Slide 2Ben Rolfe, BCA
Contribution doc.: IEEE802.15-14-0110-01-0mag Status Document in progress (15-14-0111-00-0mag) lists all the attributes, constants and parameters that specify or affect specification of MAC timing. Color coded table - what it is and where it came from Red means serious issue probably can’t ignore Yellow means may need attention Blue means minor issues (editorial or other obvious fixes) To include discussion of the issues Problem statement (conflict, unclear, etc.) Proposed fixes (eventually) Currently a work in progress Initial version to circulate among Coconspirators and be posted for next weeks call (4/March) January 2014 Slide 3Ben Rolfe, BCA
Contribution 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 conflicts amongst amendments Consider history – what’s been confused and debated Non-trivial task January 2014 Slide 4Ben Rolfe, BCA
Contribution 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 in the standard d)Reference point for timers unclear e)When/if to use CSMA a)More than 4 different CSMA scenarios need addressing 2.LIFs and SIFs a)Suggestion to replace with single IFS specification b)Ripples a lot (including into Ack timing) c)Backwards compatibility issues? January 2014 Slide 5Ben Rolfe, BCA
Contribution 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 2.macMaxFrameTotalWaitTime a)Complex definition dependent on a bunch of things 3.aBaseSlotDuration and aBaseSuperframeDuration a)Used a lot of places, needs review 4.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? January 2014 Slide 6Ben Rolfe, BCA
Contribution 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 unclear (no MAC or PHY function uses them) macTxTotal Duration: should be read-only except can be reset (i.e. not any value written) No harm done? January 2014 Slide 7Ben Rolfe, BCA
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