Short training time for MIMO systems

A method for wireless communications, comprising:

• receiving a plurality of training packets transmitted in a plurality of different directions from a device, wherein at least two of the plurality of training packets for at least two of the plurality of different directions are received via different frequencies in a radio band or using different spreading sequences;
• identifying information corresponding to at least one direction from the plurality of directions for wireless communications with the device based on the plurality of training packets;
• and
• outputting a feedback signal for transmission to the device, the feedback signal comprising the identified information corresponding to the at least one direction;
• wherein identifying the information comprises:
• determining a characteristic value for each of the plurality of training packets;
• comparing the characteristic values for the plurality of training packets;
• and
• selecting the information corresponding to the at least one direction based on the comparison.

An apparatus for wireless communications, comprising:

• a processing system configured to generate a plurality of training packets;
• a first interface configured to output each of the plurality of training packets for transmission to a device in a different one of a plurality of directions, wherein at least two of the plurality of training packets are output for transmission to the device in at least two of the plurality of directions using orthogonal transmission types;
• and
• a second interface configured to obtain a feedback signal comprising information for identifying at least one of the plurality of directions to be used for wireless communications with the device;
• wherein the first interface comprises a plurality of radio chains, wherein each of the plurality of radio chains is configured to support one of the orthogonal transmission types, and wherein each of the plurality of radio chains is coupled to a respective one of a plurality of antenna subsets of a plurality of antennas.

An apparatus for wireless communications, comprising:

• a first interface configured to receive a plurality of training packets transmitted in a plurality of different directions from a device, wherein at least two of the plurality of training packets for at least two of the plurality of different directions are received via different frequencies in a radio band or using different spreading sequences;
• a processing system configured to identify information corresponding to at least one direction from the plurality of directions for wireless communications with the device based on the plurality of training packets;
• and
• a second interface for outputting a feedback signal for transmission to the device, the feedback signal comprising the identified information corresponding to the at least one direction;
• wherein the processing system is further configured to identify the information corresponding to the at least one direction of the plurality of directions by:
• determining a characteristic value for each of the plurality of training packets;
• comparing the characteristic values for the plurality of training packets;
• and
• selecting the information corresponding to the at least one direction based on the comparison.