System and method for interpolation based transmit beamforming for MIMO-OFDM with partial feedback

A communication apparatus, comprising:

• one or more antennas;
• and
• a receiver coupled to the one or more antennas and configured to receive a plurality of output signals on a plurality of subcarriers from a transmitter of another communication apparatus, wherein:
• the receiver is configured to provide decoded signals from the received signals, and to determine and provide beamforming vectors and interpolation parameters to the transmitter;
• the beamforming vectors are associated with a subset of the plurality of subcarriers;
• the interpolation parameters are for the transmitter to use in conjunction with the provided beamforming vectors associated with a subset of the plurality of subcarriers to derive beamforming vectors for the at least one of the plurality of subcarriers not included in the subset;
• and
• the receiver is configured to subsamples the plurality of subcarriers, selects a portion of the plurality of subcarriers, and generates the interpolation parameters from the beamforming vectors associated with a subset of the plurality of subcarriers.

A communication apparatus, comprising:

• one or more antennas;
• and
• a receiver coupled to the one or more antennas and configured to receive, from a transmitter of another communication apparatus, a plurality of first signals through orthogonal frequency division multiplexing on a plurality of subcarriers;
• wherein the receiver is configured to receives the plurality of first signals, provides decoded signals indicative of the plurality of first signals, and provides precoding vectors for a plurality of the subcarriers and interpolation parameters for the transmitter to derive precoding vectors for at least one of the plurality of subcarriers not included in the subset based at least on interpolation of the precoding vectors;
• wherein the interpolation is based at least in part on the interpolation parameters;
• and
• the interpolation information includes phase values.

A communication apparatus, comprising:

• a plurality of antennas;
• and
• a transmitter coupled to the plurality of antennas and configured to provide orthogonal frequency division multiplexing to a plurality of first signals and to provide the plurality of first signals on a plurality of subcarriers for output to a receiver of another communication apparatus, wherein:
• the transmitter includes a precode matrix reconstruct unit configured to provide precoding matrices based on channel information received from the receiver of the other communication apparatus;
• the channel information includes precode vectors for a subset of the plurality of subcarriers and interpolation parameters for deriving precode vectors from at least one of the plurality of subcarriers not included in the subset
• the precode matrix reconstruct unit is configured to derive precode vectors for the at least one of the plurality of subcarriers not included in the subset in response to the provided precode vectors;
• the derivation is based at least on interpolation of the precode vectors;
• the interpolation is based at least in part on the interpolation parameters;
• and
• the receiver is configured to subsamples the plurality of subcarriers, selects the subset, evaluates the precoding vectors corresponding to the subset, and generates interpolation parameters from the evaluated precoding vectors.

The method for a communication apparatus to transmit finals to another communication apparatus using a plurality of subcarriers, comprising:

• receiving, by a transmitter of the communication apparatus, limited feedback information, wherein the limited feedback information is received from a receiver of the other communication apparatus, wherein the limited feedback information includes beamforming vectors for a subset of subcarriers and interpolation information for deriving beamforming vectors for at least one of the plurality of subcarriers from the beamforming vectors;
• deriving, by the transmitter, the beamforming vectors for at least one of the plurality of subcarriers not included in the subset b interpolating the beamforming vectors for the subset of subcarriers using the interpolation parameters;
• receiving, by the transmitter, a plurality of input signals;
• and
• providing, by the transmitter, a plurality of output signals on the plurality of subcarriers for transmission to the receiver, wherein at least one of the plurality of output finals is provided based at least on at least one of the plurality of input signals and the derived beamforming vector for the at least one of the plurality of subcarriers,
• wherein the interpolating comprises using phases values provided as part of the limited feedback information.

A method for a communication apparatus to receive signals from another communication apparatus using a plurality of subcarriers, comprising:

• receiving, by a receiver of the communication apparatus from a transmitter of the another communication apparatus, a plurality of signals on a plurality of subcarriers;
• decoding the received plurality of signals by the receiver;
• generating, by the receiver, a plurality of beamforming vectors for a subset of the plurality of subcarriers and interpolation parameters for the transmitter to derive, from the plurality of beamforming vectors for a subset of the plurality of subcarriers, beamforming vectors for at least one of the plurality of subcarriers not included in the subset;
• and
• providing, by the receiver to the transmitter, the beamforming vectors for a subset of the plurality of subcarriers and the interpolation parameters;
• wherein the interpolation parameters include phase values.

A method for a communication apparatus to transmit signals to another communication apparatus using a plurality of subcarriers, comprising:

• receiving, by a transmitter of the communication apparatus, limited feedback information, wherein the limited feedback information is received from a receiver of the other communication apparatus, and wherein the limited feedback information includes interpolation information and precoding vectors for a subset of subcarriers;
• deriving, by the transmitter, the precoding vectors for the at least one subcarrier of the plurality of subcarriers not included in the subset by interpolating the provided precoding vectors for a subset of subcarriers using the interpolation parameters;
• receiving a plurality of input signals by the transmitter;
• and
• providing, by the transmitter, a plurality of output signals on the plurality of subcarriers for transmission to the receiver, wherein at least one of the plurality of output finals is provided in response to at least one of the plurality of input signals and the derived precoding vectors,
• the limited feedback information comprises phase values.

A method for a communication apparatus to receive signals from another communication apparatus using a plurality of subcarriers, comprising:

• receiving, by a receiver of the communication apparatus from a transmitter of the another communication apparatus, a plurality of signals on a plurality of subcarriers;
• decoding the receiver;
• generating, by the receiver, a plurality of precoding vectors for a subset of the plurality of subcarriers and interpolation parameters for the transmitter to derive, from the precoding vectors for a subset of the subcarriers, precoding vectors for at least one of the plurality of subcarriers not included in the subset;
• and
• providing, by the receiver to the transmitter, the precoding vectors for a subset of the plurality of subcarriers and the interpolation parameters;
• wherein the interpolation parameters include phase values.