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Real Air-time Occupation by Beacon and Probe

Real Air-time Occupation by Beacon and Probe. Authors:. Date: 2011-11-02. Abstract. This document is not proposal. It is reporting the real Air-time occupation due to explosive increase of Smart-phones. Motivation.

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Real Air-time Occupation by Beacon and Probe

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  1. Katsuo Yunoki, KDDI R&D Laboratories Real Air-time Occupation by Beacon and Probe Authors: • Date: 2011-11-02

  2. Katsuo Yunoki, KDDI R&D Laboratories Abstract • This document is not proposal. It is reporting the real Air-time occupation due to explosive increaseof Smart-phones.

  3. Katsuo Yunoki, KDDI R&D Laboratories Motivation • 3Gmobile operators have demand to offload their data traffics to WLAN network. • Especially, they have higher demands for the locations where many people meet or stay for data offloading, because high data traffics occur at those locations. • It’s highly expected that FILS will realize transition from 3G to WLAN in very short time.

  4. Katsuo Yunoki, KDDI R&D Laboratories Real world (1) • Number of Smart-phone is increasing. • iPhone, Android, Windows-phone, Blackberry… • Smart-phone holders always touch its screen. • While its screen is activated (backlight turned on), Smart-phone starts searching surrounding WLAN-APs.

  5. Katsuo Yunoki, KDDI R&D Laboratories Real world (2) • Many Smart-phone holders are in the crowded commuter train. • Imagine what happens when the train arrives at the station. • Air monitoring was executed at a train station in Tokyo. Results are explained in the following slides.

  6. Katsuo Yunoki, KDDI R&D Laboratories Conditions • Time/Date: Around 18:00 / October 11(Tue), 2011 • Location: Shinjuku station (Keio line), Tokyo • Monitoring CH: 6CH(2,437MHz) • Monitoring period: 300 seconds (5 minutes) <Equipment> • Thinkpad X200 • Windows XP • USB Wireless Monitor Adoptor (Air Pcap NX) • Wireshark Measured CH

  7. Katsuo Yunoki, KDDI R&D Laboratories Result • Observed frames

  8. Katsuo Yunoki, KDDI R&D Laboratories Result (cont.) Frames Bytes • Time occupation is more important. • Doc. IEEE802.11-11/1031r0 was referred for time occupation analysis.

  9. Katsuo Yunoki, KDDI R&D Laboratories Transmission Rate

  10. Katsuo Yunoki, KDDI R&D Laboratories Transmission Rate (cont.)

  11. Katsuo Yunoki, KDDI R&D Laboratories Occupied Time Calculation (Beacon) Occupied Time Beacon DIFS CW TX TIME • aSlotTime: 20us • aSIFSTime: 10us • aPreambleLength: 144us • aPLCPHeaderLength: 48bits • aCWmin: 31 • aCWmax: 1023 • DIFS: 50us • CW: 310us Occupied Time = ∑((DIFS + CW + aPreambleLength + aPLCPHeaderLength/DATARATE) * TotalFrames + (TotalBytes * 8/DATARATE)) = ((50 + 310 + 144 + 48 / 1.0) * 13,861 + (1,688,640 * 8 / 1.0) + ((50 + 310 + 144 + 48 / 11.0) * 2 + (80 * 8 / 11.0) + ((50 + 310 + 144 + 48 / 24.0) * 7 + (280 * 8 / 24.0) + ((50 + 310 + 144 + 48 / 54.0) * 1 + (40 * 8 / 54.0) = 21,165,613 us (7.06%)

  12. Katsuo Yunoki, KDDI R&D Laboratories Occupied Time Calculation (Probe Request) Occupied Time Probe Request DIFS CW TX TIME Occupied Time = ∑((DIFS + CW + aPreambleLength + aPLCPHeaderLength/DATARATE) * TotalFrames + (TotalBytes * 8/DATARATE)) = ((50 + 310 + 144 + 48 / 1.0) * 6,547 + (838,510 * 8 / 1.0) + ((50 + 310 + 144 + 48 / 2.0) * 21 + (10,019 * 8 / 2.0) + ((50 + 310 + 144 + 48 / 5.5) * 13 + (12,633 * 8 / 5.5) + ((50 + 310 + 144 + 48 / 6.0) * 2 + (1,590 * 8 / 6.0) + ((50 + 310 + 144 + 48 / 9.0) * 3 + (2,631 * 8 / 9.0) + ((50 + 310 + 144 + 48 / 11.0) * 510 + (76,565 * 8 / 11.0) + ((50 + 310 + 144 + 48 / 12.0) * 2 + (3,060 * 8 / 12.0) + ((50 + 310 + 144 + 48 / 18.0) * 7 + (10,198 * 8 / 18.0) + ((50 + 310 + 144 + 48 / 24.0) * 4 + (3,154 * 8 / 24.0) + ((50 + 310 + 144 + 48 / 48.0) * 10 + (13,509 * 8 / 48.0) + ((50 + 310 + 144 + 48 / 54.0) * 20 + (17,928 * 8 / 54.0) = 10,754,454us (3.58%)

  13. Katsuo Yunoki, KDDI R&D Laboratories Occupied Time Calculation (Probe Response) Occupied Time Probe Response ACK DIFS CW TX TIME SIFS TX TIME • aSlotTime: 20us • aSIFSTime: 10us • aPreambleLength: 144us • aPLCPHeaderLength: 48bits • aCWmin: 31 • aCWmax: 1023 • DIFS: 50us • CW: 310us • ACKRate: 1Mbps • ACKLength: 14Bytes

  14. Katsuo Yunoki, KDDI R&D Laboratories Occupied Time Calculation (Probe Response)(Cont.) Occupied Time = ∑((DIFS + CW + aPreambleLength + aPLCPHeaderLength/DATARATE +aSIFSTime + aPreambleLength + aPLCPHeaderLeangth / ACKRATE + ACKLength * 8 / ACKRATE) * TotalFrames + (TotalBytes * 8/DATARATE)) = ((50 + 310 + 144 + 48 / 1.0 +10+ 144+48/1.0+14*8/1.0) * 24,606 + (2,849,896 * 8 / 1.0) + ((50 + 310 + 144 + 48 / 2.0 + 10+144+48/1.0+14 * 8 / 1.0) * 4 + (5,257 * 8 / 2.0) + ((50 + 310 + 144 + 48 / 5.5 + 10+144+48/1.0+14 * 8 / 1.0) * 7 + (10,710 * 8 / 5.5) + ((50 + 310 + 144 + 48 / 6.0 + 10+144+48/1.0+14 * 8 / 1.0) * 1 + (1,530 * 8 / 6.0) + ((50 + 310 + 144 + 48 / 9.0 + 10+144+48/1.0+14 * 8 / 1.0) * 1 + (1,530* 8 / 9.0) + ((50 + 310 + 144 + 48 / 11.0 + 10+144+48/1.0+14 * 8 / 1.0) * 15+ (13,848 * 8 / 11.0) + ((50 + 310 + 144 + 48 / 12.0 + 10+144+48/1.0+14 * 8 / 1.0) * 4 + (6,120 * 8 / 12.0) + ((50 + 310 + 144 + 48 / 18.0 + 10+144+48/1.0+14 * 8 / 1.0) * 7 + (8,212 * 8 / 18.0) + ((50 + 310 + 144 + 48 / 24.0 + 10+144+48/1.0+14 * 8 / 1.0) * 6 + (5,279 * 8 / 24.0) + ((50 + 310 + 144 + 48 / 36.0 + 10+144+48/1.0+14 * 8 / 1.0) * 3 + (4,590 * 8 / 36.0) + ((50 + 310 + 144 + 48 / 48.0 + 10+144+48/1.0+14 * 8 / 1.0) * 2 + (2,259 * 8 / 48.0) + ((50 + 310 + 144 + 48 / 54.0 + 10+144+48/1.0+14 * 8 / 1.0) * 31 + (32,100 * 8 / 54.0) = 44,215,439us (14.74%)

  15. Katsuo Yunoki, KDDI R&D Laboratories Occupied Time Calculation Result

  16. Katsuo Yunoki, KDDI R&D Laboratories Conclusion • Because of WLAN enabled devices increasing, especially Smart-phones, WLAN air circumstances are getting more crowded. • In this packet monitoring, probe responses existed 5 times more than probe requests. • To see the benefits of effective FILS, improvement of air circumstances would be needed by reducing unnecessary packet exchanges.

  17. Katsuo Yunoki, KDDI R&D Laboratories References • doc. IEEE802.11-11/1031r0

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