1. Wireless Performance Prediction (WPP) - Addressing End-User Issues
doc.: IEEE /457
November 2003
Wireless Performance Prediction (WPP) - Addressing End-User Issues
Tom Alexander
VeriWave, Inc.
Tom Alexander, VeriWave

2. Outline Common end-user issues with 802.11 WLANs
November 2003
Outline
Common end-user issues with WLANs
What WPP can do to address these issues
Tom Alexander, VeriWave

3. Common End-User Issues
doc.: IEEE /457
November 2003
Common End-User Issues
Early-adopter experience with WLANs usually positive
Lots of anecdotal problems – but users generally happy
However, corporate users have been conditioned by over a decade of wired LANs
Relative to wired LANs, wireless LANs today:
Variable and unpredictable coverage
Indeterminate capacity and coverage
Interoperation problems
Susceptibility to outside interference
Widespread corporate adoption will make these issues more visible
Current environment of folklore (e.g., people who can “see RF”) won’t go very far
Tom Alexander, VeriWave

4. Unpredictable Coverage and Capacity
doc.: IEEE /457
November 2003
Unpredictable Coverage and Capacity
WLAN coverage significantly affected by environment
Often changes over time
Walk-around site surveys normally done to address this
Expensive, but new equipment/technology starting to address
Directive antennas make this issue worse
Deterministic capacity is a bigger problem
Common question: "How much bandwidth should I be getting?”
Also:
How many clients can be assigned to a given BSS?
Exactly what improvement can be obtained with g? a?
Nobody seems to know …
No standard metrics or test methods for capacity
802.11b WLANs do NOT provide 11 Mb/s of throughput!
Variation of throughput with client loading unknown
Tom Alexander, VeriWave

5. Unreliable / Non-conformant Equipment
doc.: IEEE /457
November 2003
Unreliable / Non-conformant Equipment
Equipment reliability issues in WLANs
APs locking up, client driver issues, etc.
AP reliability issues quite difficult to handle
Inconvenient locations - safety and access problems
standards conformance is also an issue
Adherence to standards is rather spotty
Issues for future protocols (e.g., EDCA)
No standards for WLAN equipment reliability and conformance
Need to develop test methods and benchmarks
Tom Alexander, VeriWave

6. Interoperation, Interference, Security
doc.: IEEE /457
November 2003
Interoperation, Interference, Security
These are some of the biggest problems
Interoperation is a significant end-user problem
Sometimes equipment from same vendor doesn't interoperate
Standards conformance issues
Interference issues are widespread
Installers carry spectrum analyzers into end-user sites
Frequently interference occurs from other equipment
e.g., due to improper power settings
Problem will get worse over time as ISM bands fill up
Security is a well-known problem
Lots of publicity, hence many solutions coming on line
End-user apathy probably biggest concern
Need significant enhancement of metrics for interoperation and interference resistance
Tom Alexander, VeriWave

7. Need to define repeatable metrics and tests for:
doc.: IEEE /457
November 2003
Conclusions
Need to define repeatable metrics and tests for:
Conformance
Performance and capacity
Interoperability
Resistance to interference
Security
Need to ensure that metrics and methods are correlated to end-user experience
Users need to be able to rely on metrics and benchmarks to predict the installed performance of WLAN equipment
Need to ensure that metrics & methods accommodate all types of end-user WLAN equipment
The standard and the industry is continuously evolving
Tom Alexander, VeriWave