1. J. Patrick Frantz Executive Director Center for Multimedia Communication Rice University IEEE Vehicular Technology Conference April 24, 2003 J. Patrick Frantz Executive Director Center for Multimedia Communication Rice University IEEE Vehicular Technology Conference April 24, 2003 Performance of IEEE 802.11b Wireless LAN in an Emulated Mobile Channel

2. Performance of 802.11b is Well Understood for Indoor Use Outdoor and Mobile Environments Remain an Unexplored Space Plans for Use in Such Environments Prompts Further Study (e.g. Mercedes & Other Telematics Applications) Performance of 802.11b is Well Understood for Indoor Use Outdoor and Mobile Environments Remain an Unexplored Space Plans for Use in Such Environments Prompts Further Study (e.g. Mercedes & Other Telematics Applications) Motivation

3. Reviewed Literature for Measurements of Outdoor 2.4GHz ISM Channel Determined a Reasonable Set of Channel Parameters for Repeatable Experiments Precise Variation of Parameters to Measure Relationship to System Performance Used Channel Emulation for Reliable & Repeatable Results Reviewed Literature for Measurements of Outdoor 2.4GHz ISM Channel Determined a Reasonable Set of Channel Parameters for Repeatable Experiments Precise Variation of Parameters to Measure Relationship to System Performance Used Channel Emulation for Reliable & Repeatable Results Methodology

4. Experimental Setup Setup 3 Peer-to-Peer Links With H/W From 2 Different Manufacturers Wanted to Test Differences in Baseband Implementations from Two Leading Chipset Manufactureres Agere Intersil Setup 3 Peer-to-Peer Links With H/W From 2 Different Manufacturers Wanted to Test Differences in Baseband Implementations from Two Leading Chipset Manufactureres Agere Intersil

5. 2 Orinoco WLAN PC Cards (Agere Chipset) 2 D-Link Air DWL-520 WLAN PCI Cards (Intersil Chipset) TAS 4500 FLEX5 RF Channel Emulator from Spirent Communications IPERF v1.1.1 Network Testing Software 2 Orinoco WLAN PC Cards (Agere Chipset) 2 D-Link Air DWL-520 WLAN PCI Cards (Intersil Chipset) TAS 4500 FLEX5 RF Channel Emulator from Spirent Communications IPERF v1.1.1 Network Testing Software Equipment Used

6. Experimental Setup

7. Methodology Velocity - Combined Effect of Ricean and Rayleigh Fast Fading with Doppler Shift Delay Spread - Created an Ad Hoc Multipath Channel to Study Effects of Delay Spread (RMS) Similar to Power Delay Profiles from Literature Used 6-Path Model Velocity - Combined Effect of Ricean and Rayleigh Fast Fading with Doppler Shift Delay Spread - Created an Ad Hoc Multipath Channel to Study Effects of Delay Spread (RMS) Similar to Power Delay Profiles from Literature Used 6-Path Model

8. Variable Modulations - Constrained the Hardware to Specific Modulations (1, 2, 5.5 & 11Mbps) SNR - Monitored and Recorded SNR at both ends of Test Setup to Account for Path Losses in the System. Careful System Isolation and Shielding Variable Modulations - Constrained the Hardware to Specific Modulations (1, 2, 5.5 & 11Mbps) SNR - Monitored and Recorded SNR at both ends of Test Setup to Account for Path Losses in the System. Careful System Isolation and Shielding Methodology

9. Both Implementations of 802.11b Showed Significant Performance Degredations in Mobile Channels, as Expected Strong Link Between SNR and Flat Fading & Delay Spread Susceptibility Both Implementations of 802.11b Showed Significant Performance Degredations in Mobile Channels, as Expected Strong Link Between SNR and Flat Fading & Delay Spread Susceptibility Experimental Results

10. Throughput vs. Velocity in Rayleigh & Ricean Fading

11. Packet Loss vs. Velocity in Rayleigh & Ricean Fading

12. Throughput and Packet Loss vs. Delay Spread

13. Throughput & Packet Loss vs. Velocity (D-Link, Rayleigh, 15dB)

15. Throughput & Packet Loss vs. Delay Spread

16. Conclusions Typical Implementations of 802.11b are Far Less Effective in Mobile Channel However, No Reason that Current Implementations Can’t be Modified RAKE Receivers for Indoor Channels are Insufficient for Outdoor Channels with High RMS Delay Spread Slight Incompatibilities Between Chipsets Adversely Affect Performance Typical Implementations of 802.11b are Far Less Effective in Mobile Channel However, No Reason that Current Implementations Can’t be Modified RAKE Receivers for Indoor Channels are Insufficient for Outdoor Channels with High RMS Delay Spread Slight Incompatibilities Between Chipsets Adversely Affect Performance