1. Proposed Metrics for TGT and Call to Action
Month Year
doc.: IEEE /1202r0
October 2004
Proposed Metrics for TGT and Call to Action
Date: Oct 14, 2004
Author:
Charles R. Wright
Azimuth Systems
Acton, MA
Ph:
C. Wright, Azimuth Systems
C. Wright, Azimuth Systems

2. October 2004
Introduction
We’ve talked in a lot of generalities about aspects of wireless performance that impact the user experience
These can be translated into specific metrics
With corresponding test environments, etc.
We need to get down to the business of
Defining the metric
Documenting the measurement methodology
This presentation tries to provide a condensed list of metrics
C. Wright, Azimuth Systems

3. Presentations driving this one
October 2004
Presentations driving this one
11-04/987r0, “A First Stab at Metrics,” Mandeville
11-04/989r1, “Metrics for Characterizing BSS Transition Time Performance,” Wright, Polanec
11-04/1009r1, “Framework, Usages, Metrics Proposal for TGT,” Mehta, et al
11-04/1017, “Comments on Wireless Performance & Prediction Metrics,” Kobayashi, et al
11-04/1157r0, “A Metrics and Methodology Starting Point for TGT,” Wright
11-04/1156r1, “Bottom-Up Evaluation of Performance Testing,” Foegelle
C. Wright, Azimuth Systems

4. What metrics need to be defined?
October 2004
What metrics need to be defined?
Several categories
Link layer
Physical layer
Antenna performance
link management related
Whole device
Two kinds of equipment
Access points
Client stations
Environment types
Define environments that are appropriate to the specific metric
C. Wright, Azimuth Systems

5. October 2004
Link Layer Metrics
Goal of these metrics is to measure device performance under optimum conditions
“Line of sight” – no multipath
Conducted tests to avoid interference problems
Need to specify security, QoS features in use
“Throughput”
Max forwarding rate, forwarding rate at max offered load (FRMOL)
TCP data throughput
MSDU loss
Loss after wireless link retries
A function of offered load or only at maximums?
Delay (latency)
Definitely applicable to APs
Client applicability? Measurability?
Jitter
Same comment as for delay
“Rate versus Range”
Throughput versus input signal level
C. Wright, Azimuth Systems

6. Physical Layer Metrics
October 2004
Physical Layer Metrics
Receiver sensitivity at each PHY rate
Definitely measured without multipath (“line-of-sight”)
Probably measured with multipath, too
Adjacent channel interference at each PHY rate
Probably not measured with multipath
Diversity performance
Waiting for an expert to consider such a test
Applicable to all devices
Questions
Other PHY layer metrics?
Which multipath models?
Are these tests only performable using “radio control” software?
C. Wright, Azimuth Systems

7. Antenna Performance Single antenna pattern
October 2004
Antenna Performance
Single antenna pattern
One for each antenna?
Applicable to all devices
Questions
How do we deal with antenna loading caused by humans or other stuff?
How do we characterize “smart” antennas?
This slide has too much white space on it!
C. Wright, Azimuth Systems

8. 802.11 Link Management Related
October 2004
Link Management Related
AP Association Capacity, Association Rate
How many clients can an AP support? How fast does the AP associate them?
Variables: authentication method
Transition time metric
How fast does “roaming” algorithm work?
Likely we should wait until TGr is more solid
Is it a station, AP or system test?
Other metrics related to TGk
We need to investigate this – I have no idea what metrics might be needed, if any
C. Wright, Azimuth Systems

9. October 2004
Whole Device Tests
Don’t know if we actually want or need this, but it’s here so we don’t forget it
Rate vs. Range test done here too?
Anechoic Chamber
Device
Bidirectional Multipath Simulator
DUT
Adjacent Channel Intereferer
V.A.
= RF signal path
Traffic Generator & Analyzer
Ethernet
C. Wright, Azimuth Systems

10. Conclusions There is quite a list of metrics!
October 2004
Conclusions
There is quite a list of metrics!
Let’s get people to take responsibility for some of them
Want to see proposals or at least discussions of all these metrics during the 14 hours of meeting time in San Antonio
C. Wright, Azimuth Systems