Hybrid MU-MIMO spatial mapping using both explicit sounding and crosstalk tracking in a wireless local area network

A method for operating a wireless access point (WAP) having a plurality of antennas and supporting a wireless local area network (WLAN) including multiple-input multiple-output (MIMO) communications with associated stations on a selected communication channel, the method comprising acts of:

• explicitly sounding targeted stations among the associated stations for a multi-user (MU) MIMO downlink;
• determining from explicit sounding feedback received from said targeted stations both a precode matrix “Q” for spatially mapping the MU MIMO downlink and a “P1AC” matrix corresponding to a pseudo inverse of an aggregate channel between the WAP and targeted stations;
• transmitting MU-MIMO downlink packets to the targeted stations spatially mapped with precode matrix “Q”;
• receiving crosstalk feedback from at least one of the targeted stations response to the MU-MIMO downlink packets;
• combining the P1AC matrix and the received crosstalk feedback into an offset matrix;
• deriving an adjusted precode matrix “Q′” by additively combining the precode matrix “Q” with the offset matrix;
• spatially mapping subsequently transmitted MU-MIMO downlink packets to the targeted stations with the adjusted precode matrix “Q′”;
• and;
• repeating the receiving, combining, driving, and spatially mapping acts to increase an interval between explicit soundings.