Beamforming feedback options for mu-mimo

Abstract

Beamforming may be used in MIMO communication systems to further enhance spectral efficiency. Beamforming refers to beamed transmissions to a single destination (e.g., a station) at a time, to enhance the rate and/or range of transmission. To perform beamforming from a source to one or more destinations, a channel and/or beamforming matrices corresponding to the channel needs to be known at the source, which may be obtained as feedback from the destination. However, the beamforming matrices may not be smooth over frequency as it is fed back from the destination. Therefore, certain aspects of the present disclosure provide beamforming feedback options, resulting in the smoothness of a beamforming matrix.

What is claimed is: 
     
         1 . A method for wireless communications, comprising:
 estimating a channel used to receive transmissions from an access point (AP);   transmitting feedback to the AP; and   transmitting an indication that maximum-likelihood (ML) detection or minimum mean square error (MMSE) detection is used for receiving the transmissions from the AP.   
     
     
         2 . The method of  claim 1 , wherein the feedback comprises at least one of channel state information (CSI) feedback, compressed beamforming matrix feedback, and non-compressed beamforming matrix feedback. 
     
     
         3 . An apparatus for wireless communications, comprising:
 logic for estimating a channel used to receive transmissions from an access point (AP);   logic for transmitting feedback to the AP; and   logic for transmitting an indication that maximum-likelihood (ML) detection or minimum mean square error (MMSE) detection is used for receiving the transmissions from the AP.   
     
     
         4 . The apparatus of  claim 3 , wherein the feedback comprises at least one of channel state information (CSI) feedback, compressed beamforming matrix feedback, and non-compressed beamforming matrix feedback. 
     
     
         5 . An apparatus for wireless communications, comprising:
 means for estimating a channel used to receive transmissions from an access point (AP);   means for transmitting feedback to the AP; and   means for transmitting an indication that maximum-likelihood (ML) detection or minimum mean square error (MMSE) detection is used for receiving the transmissions from the AP.   
     
     
         6 . The apparatus of  claim 5 , wherein the feedback comprises at least one of channel state information (CSI) feedback, compressed beamforming matrix feedback, and non-compressed beamforming matrix feedback. 
     
     
         7 . A computer-program product for wireless communications, comprising a computer-readable medium having instructions stored thereon, the instructions being executable by one or more processors and the instructions comprising:
 instructions for estimating a channel used to receive transmissions from an access point (AP);   instructions for transmitting feedback to the AP; and   instructions for transmitting an indication that maximum-likelihood (ML) detection or minimum mean square error (MMSE) detection is used for receiving the transmissions from the AP.   
     
     
         8 . The computer-program product of  claim 7 , wherein the feedback comprises at least one of channel state information (CSI) feedback, compressed beamforming matrix feedback, and non-compressed beamforming matrix feedback.