Doc.: IEEE 802.11-10/0955r4 Submission August 2010 Bruce Kraemer, MarvellSlide 1 Smart Grid...

August 2010

Bruce Kraemer, Marvell

Slide 1

doc.: IEEE 802.11-10/0955r4

Submission

Smart Grid Technology Summer 2010 Plans

Date: 2010-August-25Abstract: Discussion PAP#2 Report

Name Company Address Phone emailBruce Kraemer Marvell 5488 Marvell Lane,

Santa Clara, CA, 95054

+1-321-751-3988 [email protected]

Jorjeta Jetcheva Itron

August 2010


Slide 2

doc.: IEEE 802.11-10/0955r4

Submission

Call Agenda

• Comments on the content of the NIST PAP#2 report, r5.

• R5 was posted at:

• http://collaborate.nist.gov/twiki-sggrid/pub/SmartGrid/PAP02Wireless/NIST_Priority_Action_Plan_2_r05.pdf

• Other items?

August 2010


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Submission

NIST Timeline

Release of draft 0.6

Release of Version 1

Draft 0.5July 28, 2010

Call for Input to Section 6August 4, 2010

End of draft 0.5 review periodSeptember 15, 2010

December 3, 2010

November 4, 2010

SGIP face-to-face, ChicagoPAP 2 meeting

OpenSG meeting, MiamiTentative PAP 2 meeting

SGIP face-to-face, St LouisTentative PAP 2 meeting

September 16, 2010

End of draft 0.6 review period

September 30, 2010

October 29, 2010

August 2010


Slide 4

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Submission

NIST Expectations

• Release 0.6 contains mature contents for all sections

• Minor changes are expected between release 0.6 and 1.0 to allow for NIST internal review process

• Technical contributions in the form comments to current draft and/or new material shall be posted on the twiki and made publicly available

• Technical contributions will be processed as they are received up to the end of the review period– Allow time to provide comment resolution and reach consensus

prior to the close of the review period.

August 2010


Slide 5

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Submission

Next NIST PAP 2 meetings

• SGIP meeting in St Louis, September 16, 2010?– Is there a need for a PAP 2 meeting?

• Co-located with OpenSG meeting, November 4, 2010, Miami FL.

• SGIP meeting, December 1-3, 2010, Chicago, IL

August 2010


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Submission

• Comments received during/following August 4

August 2010


Slide 7

doc.: IEEE 802.11-10/0955r4

Submission

Availability - 1• Hello all,• I wanted to start a discussion on Link Availability (Section 4.2.1.1 on p. 23) as a

continuation of our discussion on the call earlier today.• Currently the text mentions that Link Availability is affected by devices being in sleep

mode, or by propagation conditions and interference:• Sleep mode is generally configurable and optional (can be turned off), so one

technology is not going to offer less availability than another due to the presence of sleep mode capabilities because sleep mode can be configured appropriately or be turned off. Perhaps the availability of sleep mode should just be considered an energy efficiency mechanism and discussed in Section 4.2.2.3?

• Propagation conditions and interference affect availability of a link across all wireless technologies. What differs between different wireless technologies is how resilient they are to interference, multipath, etc., which is discussed in Section 4.2.2.1. Though these kinds of techniques can generally be employed across different technologies so it’s hard to say that they are specific to a given technology and can thus be used to compare different technologies.

• Are there additional dimensions to the Link Availability metric that are part of the intention behind this section but are not captured in the text?

• I look forward to your comments.• Jorjeta

August 2010


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Submission

Availability - 2

• Jorjeta and all,• Availability can be very focused or a rather expansive topic. I believe that sleep

mode and interference are potentially problematic in mixing concepts. • When designing an RF segment to be used by an application the duty cycle (sleep

mode) and RF link reliability are a couple of the factors that go into the availability of the link as seen by an application. For example, if one were to PING across a link from an NMS application other factors come into play. I am hitting on some of them below.

• If we are speaking to the RF link alone, availability is dependent upon, but not limited to:

• - link budget: the received signal level above the thermal noise floor necessary to receive a signal with the appropriate margin (different margins [dB] imply a different reliability [%]). NIST has produced a robust link budget calculator (available on the web) that covers the topic in much greater detail.

• - SNR margin: additional margin to account for harmful interference which is dependent on the technology in use and the permissible operational rules relating to the spectrum use/users

August 2010


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Submission

Availability - 3• Designed Availability:• However, when describing the that the radio link is needed by the application, it implies far more

than just the RF layer but also the availability of the connection (end-to-end). In many circles this is aligned more with site availability (the Uptime Institute has an excellent document covering the topic regarding Tier Classifications) and includes:

• - Hardware element availability (MTBF/MTTR)• - System component redundancy• - Distribution paths (this aligns well with the wireless topology [mesh, PTM, PTP, etc.)• - Power redundancy• - Fault tolerance• Duty Cycle: this is relative to the percentage of time the link is designed to be available for use and

tends to be dependent upon technology or operator settings (such as to conserve battery life or comply with MPE limits).

• In a single point of failure (no HW, backhaul, power redundancy design), one will find that ~99.5% is a designed system reliability. With redundancy in the systems (HW and/or power and/or distribution paths) 99.95 is achievable before RF availability is considered.

• Actual reliability will take into consideration the reliability of RF, the reliability of the system elements, the duty cycle and the operational practices of the system operator (change control, maintenance practices, etc.)

• Actual system reliability (as one would expect to see measured from a Network Management System report [i.e. an application]) must factor all these element in.

• Jake Rasweiler

August 2010


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Submission

New text for August 18 Telecon

New text for August 25 Telecon

August 2010


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Submission

Peter Ecclesine comments – Aug 11== Prepared definitions• Definition of Packet Radio should be removed.• Rate adaptation should be replaced by Link adaptation, including changing Modulation, Coding Scheme, smart antennas,

hopping patterns, http://en.wikipedia.org/wiki/Link_adaptation

• Link adaptation from Wikipedia, the free encyclopedia• Link adaptation, or adaptive coding and modulation (ACM), is a term used in wireless

communications to denote the matching of the modulation, coding and other signal and protocol parameters to the conditions on the (e.g. the pathloss, the interference due to signals coming from other transmitters, the sensitivity of the receiver, the available transmitter power margin, etc.). For example, EDGE uses a rate adaptation algorithm that adapts the modulation and coding scheme (MCS) according to the quality of the radio channel, and thus the bit rate and robustness of data transmission. The process of link adaptation is a dynamic one and the signal and protocol parameters change as the radio link conditions change -- for example in HSDPA in UMTS this can take place every 2 ms.

• Adaptive modulation systems invariably require some channel state information at the transmitter. This could be acquired in time division duplex systems by assuming the channel from the transmitter to the receiver is approximately the same as the channel from the receiver to the transmitter. Alternatively, the channel knowledge can also be directly measured at the receiver, and fed back to the transmitter. Adaptive modulation systems improve rate of transmission, and/or bit error rates, by exploiting the channel state information that is present at the transmitter. Especially over fading channels which model wireless propagation environments, adaptive modulation systems exhibit great performance enhancements compared to systems that do not exploit channel knowledge at the transmitter.

August 2010


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Submission

Link adaptation - Continued from Wikipedia

• An Example of Link Adaptation• In HSDPA link adaptation is performed by:• choice of modulation type -- the link can employ QPSK for noisy channels and 16QAM for

clearer channels. The former is more robust and can tolerate higher levels of interference but has lower transmission bit rate. The latter has twice higher bit rate but is more prone to errors due to interference and noise hence it requires stronger FEC (forward error correction) coding which in turn means more redundant bits and lower information bit rate;

• choice of FEC -- the FEC code used has a rate of 1/3, but it can be varied effectively by bit puncturing and HARQ with incremental redundancy. When the radio link conditions are good more bits are punctured and the information bit rate is increased. In poor link conditions all redundant bits are transmitted and the information bit rate drops. In very bad link conditions retransmissions occur due to HARQ which ensure correct reception of the sent information but further slow down the bit rate.

• Thus HSDPA adapts to achieve very high bit rates, of the order of 14 megabit/s, on clear channels using 16-QAM and close to 1/1 coding rate. On noisy channels HSDPA adapts to provide reliable communications using QPSK and 1/3 coding rate but the information bit rate drops to about 2.4 megabit/s. This adaptation is performed up to 500 times per second.

August 2010


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Submission

Peter Ecclesine comments – Aug 11

== Prepared definitions

• == Definitions to refine or remove:

• (unused) Generally Accepted Privacy Principles – include Web accessed groups like Truste and Better Business Bureau. (look at AT&T and Verizon Privacy Web pages)

• http://www22.verizon.com/privacy/

• http://www.att.com/gen/privacy-policy?pid=2506

• How to use the references??

• Web Portal

August 2010


Slide 14

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Submission

Needs more development

• Section 5.1.1 Indoor-indoor radio propagation models

• There should be a 5.1.2 with indoor-indoor noise including basement/garage woodworking tools, sheetmetal shop, garage door opener, washer/dryer, hair-dryer, etc. Let there be man-made noise or our models work in a vacuum.

August 2010


Slide 15

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Submission

PAP#2 _ Report_r5 –Preface Para 2

• The decision to apply wireless technologies for any given set of applications is a local decision that must take into account several important elements including both technical and business considerations. Smart Grid applications requirements must be defined with enough specificity to quantitatively define communications traffic loads, levels of performance and quality of service. Applications requirements must be combined with as complete a set of management and security requirements for the life-cycle of the system. These requirements can then used to assess the suitability of various wireless technologies to meet the requirements in the particular applications environment.

August 2010


Slide 16

doc.: IEEE 802.11-10/0955r4

Submission

Para 2 Recommended change• Reword to incorporate the idea that SG application requirements

evolve over time, yielding to experience rather than remain locked in 1989 or 1999 or 2009 economics.

• Smart Grid application requirements must be defined with enough specificity to quantitatively define communications traffic and levels of performance over the lifetime of the applications. Applications requirements must be combined with as complete a set of management and security requirements for the life-cycle of the equipment. The decisions to apply wireless for any given set of applications can then be based on expected performance and costs over the projected useful lifetimes of the spectrum and equipment.

August 2010


Slide 17

doc.: IEEE 802.11-10/0955r4

Submission

Peter Ecclesine comments – Aug 11

• == Prepared definitions

• (Remove, unused) Last Gasp – all are proprietary, none scale

• Discussion: This is a term used in utilities. There is industry text on the term,e.g:

• http://http://ewh.ieee.org/conf/tdc/IEEE_-_Outage_Management_-_042308_FINAL.pdf

August 2010


Slide 18

doc.: IEEE 802.11-10/0955r4

Submission

Availability – Comment (Aug 18)

• Comment: Jorjeta Jetcheva, Itron • The definition of Link Availability is vague (text on p. 22 (Section

4.2.1) and in Section 4.2.1.1 (p. 23)) and does not provide sufficient information to enable us to compare different wireless technologies.

• We want to know if the link is going to be available when we want to use it. This ultimately translates to the following question: if a wireless device wants to transmit a packet, how long does it need to wait before it can transmit the packet? The answer to that question ranges from “immediately” to “indefinitely” (e.g., if there is an (permanent) obstacle between the two devices that prevents communication).

• Some factors that affect how long a device has to wait before a link is available for it to use are technology independent (e.g., propagation conditions, interference), while others are technology-specific (e.g., medium access scheduling, power-save modes) and can thus be useful in comparing different wireless technologies.

August 2010


Slide 19

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Submission

Availability - Proposed Text -1 (Aug 18)

• text to be added to Section 4.2.1.1:• Link Availability refers to the ability of a device to use a wireless

link when a packet needs to be sent on the link and can be evaluated in terms of the amount of time it takes before a packet can be transmitted on the link.

• Some factors that affect how long a device has to wait before a link is available for it to use are technology-independent (e.g., propagation conditions, interference) and affect all wireless devices, while others are technology-specific (e.g., medium access scheduling, power save mechanisms) and can thus be useful in comparing different wireless technologies. It is important to note that the availability of a wireless link may not be symmetric because the wireless environment at the two endpoints of the link may be different.

August 2010


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Submission


• Propagation conditions may change dynamically and may thus affect a link’s budget and availability unpredictably, e.g., passing trucks, construction. Similarly, interference from collocated devices (not necessarily networking devices) emitting signal on overlapping frequencies may affect the quality of a link and may make it unavailable for various periods of time. Both of these factors affect link availability across wireless technologies and can be mitigated to some extent through the use of techniques aimed at improving link quality as discussed in Section 4.2.2.1.

• Power save mechanisms may affect the ability of a device to receive traffic during the times it is in power save mode, however, they can typically be configured or turned off depending on the level of availability required by a specific network.

August 2010


Slide 21

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Submission


• Medium access scheduling may be deterministic (e.g., transmissions follow a schedule computed/dictated by a “coordinator” for the link, e.g., a base station), or may incorporate a non-deterministic component (e.g., random access mechanisms, including backoff when a device senses the medium to be busy), and typically depends on the number of devices trying to use a link simultaneously, and the amount and relative priority of the traffic they are transmitting, e.g., higher priority packets may get preferential access to the wireless medium causing lower priority packets to wait before they can be transmitted. (The effects of interference caused by transmissions by devices other than those trying to use the same link are taken into account in the technology-independent discussion and is not taken into account as part of the medium access delay.)

• Medium access delay is a technology-specific metric that can be a useful tool for comparing link availability across different wireless technologies. For example, given a number of devices trying to use a wireless link simultaneously, we can estimate the average time a device has to wait before it can access the medium by taking into account scheduling and backoff parameters used for timing packet transmission attempts.

August 2010


Slide 22

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Submission

Next call – September 1 – 2pm EDT

• Review any additional submissions

• to Sections 1-5

• Or to section 6

August 2010


Slide 23

doc.: IEEE 802.11-10/0955r4

Submission

Call for Contributions to Section 6

• Suggested Outline

• Factors affecting performance, i.e. reliability, delay, throughput– Channel conditions such as distance, transmitted power,

interference, propagation environment

– Traffic load

– Number of users

• Seeking volunteers?

August 2010


Slide 24

doc.: IEEE 802.11-10/0955r4

Submission

Section 6 – Default Suggestions• 6. Findings / Results• Does wireless technology X meet SG-Network requirements

– Performance Metrics– Reliability– Latency– Scalability– meets throughput needs– handles the number of devices needed– range– interference immunity– By actor to actor / Link by link which is the best to use– How does its work in urban, sub-urban, rural– How well does it propagate (e.g. walls, basements, vaults, clutter, hills)– scalability over a quantity of end points– Equipment required to operate– Include processing time between actor to actor

Doc.: IEEE 802.11-10/0955r4 Submission August 2010 Bruce Kraemer, MarvellSlide 1 Smart Grid...

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