Wireless Performance Prediction (WPP) - Addressing End-User Issues

1. Wireless Performance Prediction(WPP)-Addressing End-User Issues Tom Alexander tom@veriwave.com VeriWave, Inc. Tom Alexander, VeriWave

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

3. 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 • 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 802.11g? 802.11a? • 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 • 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 • 802.11 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 • 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 802.11 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. 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