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[Why Implicit TxBF is Better for 11ac]

[Why Implicit TxBF is Better for 11ac]. Authors:. Date: 2010-07-12. Abstract. There are two major types of transmit beamforming (TxBF) in 11n Explicit Feedback TxBF Implicit Feedback TxBF The document highlights various benefits in adopting Implicit for 11ac

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[Why Implicit TxBF is Better for 11ac]

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  1. [Why Implicit TxBF is Better for 11ac] Authors: Date: 2010-07-12 Yuichi Morioka, Sony Corporation

  2. Abstract • There are two major types of transmit beamforming (TxBF) in 11n • Explicit Feedback TxBF • Implicit Feedback TxBF • The document highlights various benefits in adopting Implicit for 11ac • Less complexity at the STA than Explicit • Lower overhead than Explicit • Better performance in varying channel than Explicit • It is proposed to utilize Implicit Feedback TxBF for 11ac • or maintain the current options as in 11n, in order to avoid repeating the same discussion that happened in 11n Yuichi Morioka, Sony Corporation

  3. Review of TxBF types in 11n • Implicit TxBF: Sounding Frame (Staggered or NDP) is sent by the STA, and the channelstate info is calculated at the AP • Explicit TxBF: Sounding Frame is sent by the AP, the channel state info is calculated at the STA, and is transmitted back to the AP • Three non-compatible types of channel information are defined in 11n Yuichi Morioka, Sony Corporation

  4. Merit of Implicit 1: Less Complexity at STA • The spirit of 11ac is put the complexity to the AP by the use of SDMA • However, if Explicit TxBF is adopted, the channel state information must be calculated at the STA, which obviously adds complexity at the STA • With Implicit, STA just sends the Sounding and not worry about anything else Yuichi Morioka, Sony Corporation

  5. Merit of Implicit 2: Less Overhead • In 11ac, in order to simultaneously send Data to multiple STAs, training must be done with all corresponding STAs • Channel state info must be collected from all STAs resulting in large overhead • With Implicit, only Sounding is collected from the STAs, so less overhead Yuichi Morioka, Sony Corporation

  6. Merit of Implicit 3: Fresh Channel • Because of the varying channel, you want the Sounding to be sent as close as possible to the SDMA data • However, in Explicit the channel state info must be sent after the Sounding frame so, it will take more time after the Sounding to send SDMA Data • With Implicit, SDMA Data is sent right after Sounding so a fresh channel is used Yuichi Morioka, Sony Corporation

  7. Conclusion • Two major types of TxBF in 11n are introduced • Explicit Feedback TxBF • Implicit Feedback TxBF • The document highlighted various benefits in adopting Implicit for 11ac • Less complexity at the STA than Explicit • Lower overhead than Explicit • Better performance in varying channel than Explicit • It is strongly recommended to utilize Implicit Feedback TxBF for 11ac • or maintain the current options as in 11n, in order to avoid repeating the same discussion that heppened in 11n Yuichi Morioka, Sony Corporation

  8. Strawpoll • Do you agree with any of the merits of Implicit TxBF described in this document (doc818r01)? • Yes31/No1/Abs20 Yuichi Morioka, Sony Corporation

  9. Thank you! Yuichi Morioka, Sony Corporation

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