1. doc.: IEEE 802.15-09-0673-00 Submission September 2009 Tim Godfrey, EPRISlide 1 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Metrics to support extended length MPDU] Date Submitted: [22 September, 2009] Source: [T Godfrey] Company [EPRI] Address [3420 Hillview Avenue, Palo Alto, California 94304] Voice:[913-706-3777], E-Mail:[tim.11.g@gmail.com] Re: [In response to chair’s request at Joint session of TG4e, TG4f, and TG4g, 21 September 2009] Contributors: [Tim Godfrey (EPRI), Craig Rodine (EPRI)] Abstract:[Proposal for extending metrics available through MAC SAP to enable higher layers to implement dynamic fragmentation (MTU) to enable reliable transfer of 1500 octet packets called for in 15.4g PAR] Purpose:[To be considered during 802.15.4e standard development process] 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.

2. doc.: IEEE 802.15-09-0673-00 Submission September 2009 Tim Godfrey, EPRISlide 2 IEEE P2030 Smart Grid Interoperability Standards Development Kick-Off Meeting June 3-5, 2009 Hosted by INTEL, Corporation, Santa Clara, CA Metrics to support extended MPDU lengths in 802.15.4 Tim Godfrey EPRI

3. doc.: IEEE 802.15-09-0673-00 Submission September 2009 Tim Godfrey, EPRISlide 3 Introduction: the issue The 802.15.4g PAR calls for “PHY frame sizes up to a minimum of 1500 octets”. –The intention behind this requirement is to allow direct support of IP packets The 802.15.4 MAC was designed for 127 byte packets –Long packets and low rates = transmission duration up to of 100s of mS. –Channel impairments and interference bursts may occur in the range of a few mS. –Result: very low probability of transmission success

4. doc.: IEEE 802.15-09-0673-00 Submission September 2009 Tim Godfrey, EPRISlide 4 Proposal Extend the 802.15.4 MAC to provide a set of metrics to allow higher layers to implement dynamic fragmentation based on channel conditions –Extend MLME SAP to convey necessary MAC information to higher layers (to support dynamic fragmentation at network layer – E.G IETF 6LOPAN) In poor channel conditions, and/or at very low rates, upper layers will fragment 1500 octet packets into smaller MSDUs to be carried over 802.15.4 network –The algorithm for deriving optimal MSDU sizes based on the provided metrics is out of the scope of this standard New metrics are added by extending MLME-GET.request –New MAC PIB attributes are added to Table 127 –Where necessary, PLME-GET.request and PLME-GET.confirm will be extended to support new attributes

5. doc.: IEEE 802.15-09-0673-00 Submission September 2009 Tim Godfrey, EPRISlide 5 PHY Metrics FunctionExistingNeededNice To Have LQI – link quality indicatorPD-DATA.indication ppduLinkQuality (6.13.8) MLME-BEACON-NOTIFY.indication PANDescriptor LinkQuality (7.1.5.1.1) PHY rates and modulations (rate implies modulation) PD-DATA.indication DataRate RSSI – Receive Signal Strength IndicatorPLME-ED provides RSSI when accompanying a valid received packet RSNI – Receive Signal to Noise IndicatorX ANPI – Average Noise Power Indicator (indication of the average noise plus interference power measured when the channel is idle) PLME-ED.confirm EnergyLevel Explicit measurement of clear channel? Noise HistogramX

6. doc.: IEEE 802.15-09-0673-00 Submission September 2009 Tim Godfrey, EPRISlide 6 MAC Metrics FunctionExistingNeededNice to have Retry CountX Multiple Retry CountX Transmit Failure CountX FCS Error CountX Duplicate Frame CountX ACK Failure CountX Successful RX frame countX Successful TX frame countX Security Failure countX These counters are accessed as new MAC PIB Attributes

7. doc.: IEEE 802.15-09-0673-00 Submission September 2009 Tim Godfrey, EPRISlide 7 Statistics Handling PHY-related metrics are associated with specific devices by correlating with source address It is not mandatory to maintain tables of measurements (per address) within the MAC –Metrics are passed directly to higher layers for use by fragmentation (MTU) decision algorithm

8. doc.: IEEE 802.15-09-0673-00 Submission September 2009 Tim Godfrey, EPRISlide 8 For further consideration Is there a need to convey metrics over the wireless link? I.E. is it necessary for a coordinator to request metrics from a device? –This would require defining new frame formats Do we need to provide a reset function for MAC stat counters? –Can we leave it to upper layers to calculate differences and note when wrap around occurs? How many bits are needed for each counter? –Answer depends on how often upper layers will check counters, and rate of incrementing.