Abstract: In this talk, a brief summary of 802.11ac features compared to the previous two major 11 standards, 11n and 11a will be presented, and the most of the material will cover the PHY parts. The detail preamble design will be explained. There are Short Training Field (STF), Long Training Field (LTF), and SIG field in a preamble. The design procedure of these fields will be presented. The received STFs in each STA will estimate the Packet Detection, Coarse Carrier Freq Offset (CFO), and the Symbol Timing Offset, whereas the LTFs will estimate the Fine CFO, and the channel between AP and STA. The detail, Synchronization and Channel Estimation operation through these reference signals will be explained. The Beamforming (BF) is an important issue in the 11ac and 11n, and the implementation example of angle quantization BF feedback will be addressed. There were several BF feedback methods in 802.11n, but one explicit feedback method, the angle quantized BF feedback, out of those feedback methods survived in 802.11ac. We'll think together why the BF feedback has been simplified in 802.11ac. A reconstruction example of BF matrix in the AP after receiving the feedback packets from a STA will be also presented. Bio: Dr. Junghoon Suh obtained his Master degree from Arizona State University in 1997, and Ph.D degree from University of Tennessee in 2004. Then he worked at Samsung Advanced Institute of Technology as a research staff in the field of Wi-Fi Standards, algorithm development of advanced MIMO, and software defined radio (SDR) implementation. In 2011, he has joined Huawei Ottawa R&D center, working in the field of Wi-Fi Standards.