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Multiple RF operation for 802.11ax OFDMA

Multiple RF operation for 802.11ax OFDMA. Authors:. Date: 2014-09-xx. Contention overhead & MAC efficiency. 11ax is targeting to achieve throughput enhancement of 4(~10) times Contention overhead of WLAN[1] MAC efficiency drops as STA density increases.

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Multiple RF operation for 802.11ax OFDMA

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  1. Multiple RF operation for 802.11ax OFDMA Authors: • Date:2014-09-xx Woojin Ahn, Yonsei Univ.

  2. Contention overhead & MAC efficiency • 11ax is targeting to achieve throughput enhancement of 4(~10) times • Contention overhead of WLAN[1] • MAC efficiency drops as STA density increases Woojin Ahn, Yonsei Univ.

  3. Multiuser widerband(OFDMA) operation • Exploiting OFDM & Widerband operation • Contention isolation Aggregated Throughput↑ MAC efficiency ↓ Contention overhead ↓ MAC efficiency↑ Faster processing for upper layer(TCP) Woojin Ahn, Yonsei Univ.

  4. Expected form of MU widerband op.(DL) • Adjusting tx/rx timing for AP • Various data length • ACK cannot be received while AP is transmitting DL data • Unnecessary channel occupation, delay Woojin Ahn, Yonsei Univ.

  5. Expected form of MU widerband op.(UL) • Difficult to synchronize medium access of multiple STAs • Fast transition of tx/rx for short messages (RTS/CTS) • Impossible to take additional access • (Specific access protocols need further discussion) Woojin Ahn, Yonsei Univ.

  6. Limitation of single RF chain • Rectangular shaped widerband operation • Transmission/reception at a time • Inefficient channel usage • Unsuitable for multiuser operation • Adopting multiple RF chains at AP Woojin Ahn, Yonsei Univ.

  7. Multiple RF structure • Multiple RF • Independent transmission/reception among different RF chains Woojin Ahn, Yonsei Univ.

  8. Utilizing Multiple RF(1) • Single RF chain Woojin Ahn, Yonsei Univ.

  9. Utilizing Multiple RF(1) • Dual RF chains Woojin Ahn, Yonsei Univ.

  10. Utilizing Multiple RF(1) • Dual RF chains Woojin Ahn, Yonsei Univ.

  11. Utilizing Multiple RF(1) • Dual RF chains Woojin Ahn, Yonsei Univ.

  12. Utilizing Multiple RF(1) • Multiple RF chains Woojin Ahn, Yonsei Univ.

  13. Utilizing Multiple RF(2) • Unrestricted preferred CH access Woojin Ahn, Yonsei Univ.

  14. Multiple RF extension(1) • Dual wi-fi[2], DL only CH • Traffic asymmetry Woojin Ahn, Yonsei Univ.

  15. Multiple RF extension(2) • DCF/PCF dual Channel • FTP downloading, HTTP -> contention based CH • Streaming, Control/management data -> scheduling based CH • Contention isolation / Coordination gain Woojin Ahn, Yonsei Univ.

  16. Conclusion • Contention overhead is one of the biggest reasons that reduces the MAC efficiency of 802.11 networks • Multiuser widerband operation(OFDMA) might play a key role to reduce the contention overhead and enhance the overall MAC efficiency • However, existing single RF chain structure is not suitable for MU widerband operation • Adopting multiple RF chains at AP could increase the utility of MU widerband operation • Multiple RF chains operation should be investigated more in 802.11ax Woojin Ahn, Yonsei Univ.

  17. References • [1] 11-13-0505-00-0hew-mac-efficiecy-analysis-for-hew-sg • [2] 11-13-1409-00-0hew-dual-wi-fi-dual-channel-wi-fi-for-congested-wlans-with-asymmetric-traffic-loads Woojin Ahn, Yonsei Univ.

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