802.11ac

802.11ac: A Survival Guide by Matthew S. Gast
https://www.oreilly.com/library/view/80211ac-a-survival/9781449357702/ch04.html

[32] Omni antenna coverage is not a perfect sphere. It’s usually more like a doughnut with an AP at the center and the torus spread out horizontally. Most AP coverage diagrams are drawn from the perspective of an observer looking down on the network from the top, though, so omnidirectional antennas are depicted as a having a circular coverage area.
[33] Beamforming is sometimes also called beam steering, for obvious reasons. I prefer beam steering as a term because it describes the effects of the process better, but I have chosen to use the term preferred by the authors of the standard in this book.
[34] In practice, beamforming is easier to do in the “downstream” (AP to client) direction because APs have more sophisticated antenna arrays.
[35] For more information, see my blog post at http://blogs.aerohive.com/blog/the-wi-fi-security-blog/did-the-fcc-really-limit-80211ac-beamforming.
[36] One subtle distinction between 802.11n and 802.11ac is that the latter does away with the unequal modulation (UEQM) modes. UEQM was originally standardized because one effect of beamforming may be to emphasize that certain carriers or paths are less able to sustain high data rates, due to frequency-specific effects. One of the reasons why UEQM was never widely deployed with 802.11n is that very few 802.11n implementations ever made use of explicit beamforming.
[37] Timing for a sounding exchange is determined mainly by the size of the feedback matrix. Both the NDP Announcement and the NDP are fairly short. After gaining control of the channel, the NDPA and NDP frames require about 100 microseconds. For computing the duration required for the feedback matrix, it’s necessary to make an assumption about the achievable data rate, which is itself a function of the channel bandwidth and modulation and coding. To get to a rough figure of 500 microseconds, I assumed that the channel was able to support a data rate at the lower end of the middle range of data rates.
[38] Feedback matrix calculations are not for the faint of heart. 802.11ac borrows heavily from the beamforming procedures first established in 802.11n. If you want the gory details of the matrix math used to calculate the feedback matrix, see clause 20.3.12.3 in 802.11-2012, and read up on Givens rotations, which are named after the scientist at the Argonne National Laboratory who invented them.

#論文等

Feasibility study of antenna synthesis using hyper beamforming
February 2019Heliyon 5(2)
Dawit Hadush HailuDawit Hadush Hailu

Efficient Evaluation of Energy Focusing Based on Eigen-Beamforming
February 2019
Conference: EuCAP 2019At: Krakow
Thomas PaironThomas PaironClaude OestgesClaude OestgesMaxime DrouguetMaxime DrouguetChristophe Craeye

Feasibility study of antenna synthesis using hyper beamforming
February 2019Heliyon 5(2):e01230
DOI: 10.1016/j.heliyon.2019.e01230.
Gebrehiwet Gebrekrstos LemaGebrehiwet Gebrekrstos Lema

Beamforming transmission with analog hardware resource sharing
February 2019
Patent: US10218550B1
Projects: mmWave systemBeamforming
Kyeong Jin KimKyeong Jin KimZhengyu PengBingnan WangBingnan WangKoon TeoKoon Teo

On The Equivalence between Hybrid and Full Digital Beamforming in mmWave communications
April 2019
Conference: 2019 26th International Conference on Telecommunications (ICT)At: Hanoi, Vietnam
Mohamed ShehataMohamed ShehataAli MokhAli MokhMatthieu CrussièreMatthieu CrussièreShow all 5 authorsPatrice PajuscoPatrice Pajusco

Revisiting beamforming under the prism of inverse methods
February 2019
DOI: 10.1117/12.2509452
Conference: Physics and Simulation of Optoelectronic Devices XXVII
Costas ValagiannopoulosCostas ValagiannopoulosVassilios KovanisVassilios Kovanis

Spatially Controlled Relay Beamforming
October 2018IEEE Transactions on Signal Processing PP(99):1
DOI: 10.1109/TSP.2018.2875896
Dionysios KalogeriasDionysios KalogeriasAthina PetropuluAthina Petropulu

On the Sparse Beamformer Design
October 2018Sensors 18(10):3536
DOI: 10.3390/s18103536
LicenseCC BY 4.0
Mingjie GaoKa YiuSven NordholmSven Nordholm

Learning beamforming in ultrasound imaging
December 2018
LicenseCC BY-NC-SA 4.0
Project: Data-driven methods to improve ultrasound imaging
Sanketh VedulaSanketh VedulaOrtal SenoufGrigoriy ZurakhovGrigoriy ZurakhovShow all 6 authorsMichael ZibulevskyMichael Zibulevsky

Feasibility study of antenna synthesis using hyper beamforming
February 2019Heliyon 5(2)
DOI: 10.1016/j.heliyon.2019.e01230
LicenseCC BY-NC-ND 4.0
Gebrehiwet LemaGebrehiwet Lema

文書履歴(document history)

ver. 0.01 初稿 20190321 午後
ver. 0.02 見出し訂正 20190321 夕
最後までおよみいただきありがとうございました。

いいね　💚、フォローをお願いします。

Thank you very much for reading to the last sentence.

Please press the like icon 💚　and follow me for your happy life.