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 b Wireless LAN in an Emulated Mobile Channel

Performance of b 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 b 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

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

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

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

Experimental Setup

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

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

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

Throughput vs. Velocity in Rayleigh & Ricean Fading

Packet Loss vs. Velocity in Rayleigh & Ricean Fading

Throughput and Packet Loss vs. Delay Spread

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

Throughput & Packet Loss vs. Delay Spread

Conclusions Typical Implementations of b 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 b 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