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WAVE High Speed Testing

Wireless Access in Vehicular Environments for the 5.9 GHz band. WAVE High Speed Testing. Repeat testing for FreeSpace and Atheros 802.11a (not R/A) Testing in July showed failures with not enough explanation about the cause(s)

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WAVE High Speed Testing

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  1. Wireless Access in Vehicular Environments for the 5.9 GHz band WAVE High Speed Testing Broady Cash, ARINC

  2. Repeat testing for FreeSpace and Atheros 802.11a (not R/A) Testing in July showed failures with not enough explanation about the cause(s) Emphasis should be on equal dB margin zones, not equal size zones Background Broady Cash, ARINC

  3. Testing performed at Maryland International Raceway, Budds Creek, MD. RSU antenna mounted on cherry picker. OBU equipped vehicle makes 10 passes through the zone at 35, 60, 80, 100, & 120 mph. Test Description Broady Cash, ARINC

  4. Budds Creek Broady Cash, ARINC

  5. RSU Antenna Broady Cash, ARINC

  6. OBU Antenna Broady Cash, ARINC

  7. July RSU Antenna Height: 19 feet 5 inches RSU bore sight angle: 20 Deg. from vertical OBU Antenna Height: 4 feet OBU bore sight angle: 25° from horizontal August RSU Antenna Height: 19 feet 9 inches RSU bore sight angle: 20 Deg. from vertical OBU Antenna Height: 4 feet OBU bore sight angle: 35° from horizontal Antenna Positions Broady Cash, ARINC

  8. July Wanted: same size CZ ~ 12-15 feet Atheros: Attenuation: 42 dB CZ ~13 feet FreeSpace: Attenuation: 29 dB CZ ~15 feet August Wanted: equal dB margin zones ~ 5 dB Result: very different zones (6 ft. vs. 14 ft.) Compromise: Atheros : attn 26dB, (15 dB margin) CZ ~20 ft. FreeSpace: attn 20dB (19 dB margin) CZ ~18 ft. Light beams used to limit CZ to 12 ft. Communication Zone (CZ) Broady Cash, ARINC

  9. RSU OBU BST VST Sleep Basic Protocol Broady Cash, ARINC

  10. Service Channel protocol with ACK BST transmitted in all 20 slots of a frame (L2) . When the OBU receives the BST, a VST is returned, in all slots of a single frame (L2). If a Sleep is not received after 200 polls, the OBU retransmits the VST (L7). If Sleep is not received within 16 msec of the BST, the “try” is terminated. FreeSpace Protocol Details Broady Cash, ARINC

  11. DCF (ACK inherent) RSU L2 transmits the BST up to 7 times (until ACK) When the OBU receives the BST, a VST is returned. Up to 7 L2 attempts (until ACK) If a Sleep is not received after 200 polls, the OBU (L7) retransmits the VST. If Sleep is not received within 16 msec of the BST, the “try” is terminated. Atheros Protocol Details Broady Cash, ARINC

  12. Nr of Tries – nr of L7 BST’s between light beam and final sleep Access Time – first light beam to first BST received at OBU Transaction Time – final BST to final sleep received at OBU Communication Time – first BST to final sleep received at OBU Measurements (35 to 100 mph) Broady Cash, ARINC

  13. Nr of Tries – nr of L7 BST’s between light beam and final sleep Access Time – first light beam to first BST transmitted from RSU Transaction Time – final BST to final sleep transmitted from RSU Communication Time – first BST to final sleep transmitted from RSU Measurements (120 mph) Broady Cash, ARINC

  14. FreeSpace requires association before transaction RSU signal manually switched to “road coverage” antenna until just before the zone reached, then signal restored to spot. Atheros OBU was “hardwired” to assume association with RSU complete Association Broady Cash, ARINC

  15. Results Broady Cash, ARINC

  16. ETC Scorecard Broady Cash, ARINC

  17. FreeSpace 49/50 runs succeeded with one L7 BST try 1 run at 35 mph needed two L7 BST tries to complete the transaction OBU Did not receive first BST Atheors 49/50 runs succeeded with one L7 BST try 1 run at 100 mph needed two L7 BST tries to complete the transaction OBU Did not receive first BST Number of Trials: FS, Atheros Broady Cash, ARINC

  18. FreeSpace Access Time Broady Cash, ARINC

  19. FreeSpace Access Time - Detail Broady Cash, ARINC

  20. Atheros Access Time Broady Cash, ARINC

  21. Atheros Access Time – Detail Broady Cash, ARINC

  22. Access Time: Detail Histograms FreeSpace Atheros Broady Cash, ARINC

  23. FreeSpace Transaction Time Broady Cash, ARINC

  24. Atheros Transaction Time Broady Cash, ARINC

  25. Transaction Time FreeSpace Atheros Broady Cash, ARINC

  26. Transactions Time CDFs Broady Cash, ARINC

  27. FreeSpace Communication Time Broady Cash, ARINC

  28. FreeSpace Communication Time Broady Cash, ARINC

  29. Atheros Communication Time Broady Cash, ARINC

  30. Both radios completed all transactions. Each radio had one run with two L7 BST tries. Transaction Time for both radios is 6 msec or less, 95 % of the time. Observations Broady Cash, ARINC

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