Patent ID: 9647736
Date: 2017-05-09
CPC Classifications: H04B

Claim:
1. A wireless access point (WAP) supporting wireless communications with associated stations on a selected communication channel; and the WAP comprising: a plurality of antennas; a plurality of components coupled to one another to form a plurality of the transmit and receive paths each coupled to as corresponding one of the plurality of antennas for multiple-input multiple-output (MIMO) communications on the selected communication channel; a multi-user (MU) grouping module coupled to the plurality of components to select a MU group of at least two of the associated stations and to allocate an aggregate number of streams for transmission to the MU group; a constrained station identifier coupled to the plurality of components to identify if any of the stations in the MU group are constrained stations that do not support training on the aggregate number of streams allocated by the MU grouping module, and in response to the identification of any constrained stations to further identify a limit on the number of training streams supported by a most constrained one of the stations; a channel sounder coupled to the plurality of components to sound the stations in the MU group for channel state information (CSI); a precode matrix calculator coupled to the channel sounder to calculate from the CSI obtained by the channel sounder a full precode matrix “Q” having a column dimension equal to the aggregate number of streams allocated by the MU grouping module, for precoding communications to the MU group; a precode matrix compressor responsive to the identification of any constrained stations in the MU group by the constrained station identifier, to compress the full precode matrix Q into a compressed precode matrix “C(Q)” having a column dimension equal to the limit on the number of training streams supported by the most constrained one of the stations in the MU group as identified by the constrained station identifier; and a spatial mapper component of the plurality of components spatially mapping an OFDM wireless transmission of a downlink MU-MIMO packet to the stations in the MU group, including spatially mapping the transmission of a payload portion of the MU-MIMO downlink packet using the full precede matrix Q and spatially mapping the transmission of a training portion of the MU-MIMO downlink packet using a selected one of the compressed precode matrix C(Q) responsive to the identification by the constrained station identifier of a constrained station in the MU group and the full precode matrix Q absent said identification.