March 2005

Tom AlexanderSlide 1

IEEE 802.11T

Tom Alexander

VeriWave, Inc.

March 2005

March 2005

Tom AlexanderSlide 2

What is IEEE 802.11T?

• Task group within the IEEE 802.11 Wireless LANs group

• Formally created in August 2004 to recommend methods for testing performance of 802.11 devices and systems– Goal: establish a common framework, terminology and

methodology for the 802.11 Wireless LAN industry

March 2005

Tom AlexanderSlide 3

Objectives of 802.11T

• Scope and purpose– Official scope: “to provide a set of performance metrics,

measurement methodologies, and test conditions to enable measuring and predicting the performance of 802.11 WLAN devices and networks at the component and application level”

– Official purpose: “to enable testing, comparison, and deployment planning of 802.11 WLAN devices based on a common and accepted set of performance metrics, measurement methodologies and test conditions”

• Output will be IEEE 802.11.2, a “Recommended Practice”– Uses the word “should”

March 2005

Tom AlexanderSlide 4

Vital Statistics• Officers

– Chair: Charles Wright, Azimuth Systems– Technical Editor: Tom Alexander, VeriWave Inc– Secretary: none yet

• About 15 – 20 active members– Sometimes up to 40 people attend

• Involvement from a broad cross-section of the WLAN industry– System and chipset vendors: Dell, Intel, Broadcom, AMD, Atheros, …– Test equipment vendors: Spirent, Azimuth, Rohde & Schwarz, VeriWave, …– Installation tools & services vendors: Wireless Valley, …– Users: Microsoft, UBC, UNH-IOL, …– And some just plain interested folks

• Activity– Meets during every 802.11 interim or Plenary for about 10 – 16 hours– Weekly teleconferences (Thursday mornings, 9AM PST)– Ad-hoc teleconferences

March 2005

Tom AlexanderSlide 5

Work To Date

• Scope and framework– What kind of metrics? What sort of approach to measurement? What layer(s) do we

include?– Diverse group; these discussions help build common understanding– General consensus on some key issues

• Both open-air and conducted metrics should be specified• Metrics should be somehow tied to end-user experience• Etc.

• Draft structure– Proposed templates for the overall draft and for individual measurement

descriptions have been created, plus proposals for the organization of the standard

• Terminology– Key discussion point in group to date (e.g., “What is a metric? What does

‘controlled environment’ imply?)

• Lots of “this is how we did it” and “this is how we should do it” presentations– Very useful in assessing what is possible and what is not– Wireless measurement methodologies differ somewhat from wired

March 2005

Tom AlexanderSlide 6

Recent and Upcoming Work

• Convergence on some basic terminology– Examples: ‘controlled test environment’, ‘conducted test’, ‘over-

the-air test’, ‘interference’, etc.– Most of these are specific to wireless testing (as opposed to

benchmarking in general)• Not much disagreement (yet!) on terms such as latency, throughput,

loss, delay, etc.

• Adoption of ground rules before voting on formal proposals– Requirements for a proposal to be considered “complete”– Format and content of formal metrics & methodology proposals

• Timeline for first draft standard: uncertain at the moment

March 2005

Tom AlexanderSlide 7

For Further Information …

• The 802.11 document server– www.802wirelessworld.com – 802.11 document server with 802.11T

contributions

– Examples of interesting contributions:• # 11-04-1160-00-000t Enabling Prediction of Wireless Performance

• # 11-04-1202-00-000t Proposed Metrics and TGT Call to Action

• # 11-04-1222-01-000t Measurement Methodology Proposal Based on Approved Framework

• # 11-05-1582-00-000t Environment and Metrics: Laboratory vs. Real-world

• # 11-05-0002-00-000t Proposed TGT Document Structure

• # 11-05-0004-01-000t TGT Terminology and Concepts

• The 802.11T reflector

• March 802.11 Plenary– March 14th to 18th, Atlanta, GA