Author: RaktimR_11 Version: **
CYW43455 is a single-input single-output (SISO) chip; therefore, it is capable of being only an 802.11ac explicit beamformee.
Typically, an access point (AP) can use either a single TX chain or use space time block coding (STBC) using two TX chains, provided the SISO STA device claims support for STBC or explicit beamforming.
If explicit beamforming is used, the AP will send out a Null Data Packet (NDP) announcement, followed by an NDP frame using different angles given by an AP for each subcarrier. The STA (CYW43455, in this case) will need to build a feedback “V” matrix and then send the same back to the AP. The AP then willl use this feedback matrix to build its steering or “Q” matrix, which it would use to send data to CYW43455 down the link.