Efficient search of precoders in precoded MIMO systems

A first communication device configured to receive precoded signals from a second communication device via a wireless channel, the first communication device comprising:

• a network interface having one or more integrated circuits configured to
• calculate a set of first metrics using (i) channel information corresponding to the wireless channel and (ii) one or more precoders, wherein each metric of the set of first metrics corresponds to a respective set of a plurality of sets of codebook precoders, wherein each set includes a same number of precoders,
• select, based on (i) the set of first metrics and (ii) a first selection criteria, a set of codebook precoders from the plurality of sets of codebook precoders,
• in response to selecting the set of codebook precoders,
• calculate a set of second metrics at least by calculating each metric in the set of second metrics using a respective codebook precoder in the selected set of codebook precoders, and
• select, based on (i) the set of second metrics and (ii) a second selection criteria, a codebook precoder from the selected set of codebook precoders, and
• cause an indicator of the selected codebook precoder to be transmitted to the second communication device.

A tangible, non-transitory computer-readable medium storing instructions that, when executed by one or more processors, cause the one or more processors to:

• calculate a set of first metrics using (i) channel information corresponding to a wireless channel, wherein the wireless channel is utilized to send precoded signals to a first communication device from a second communication device, and (ii) one or more precoders, wherein each metric of the set of first metrics corresponds to a respective set of a plurality of sets of codebook precoders, wherein each set includes a same number of precoders;
• select, based on (i) the set of first metrics and (ii) a first selection criteria, a set of codebook precoders from the plurality of sets of codebook precoders;
• in response to selecting the set of codebook precoders,
• calculate a set of second metrics at least by calculating each metric in the set of second metrics using a respective codebook precoder in the selected set of codebook precoders, and
• select, based on (i) the set of second metrics and (ii) a second selection criteria, a codebook precoder from the selected set of codebook precoders;
• and
• cause the selected codebook precoder to be applied to a signal to be transmitted from the second communication device to the first communication device.