Feedback of sparse correlation matrix for multiple-input and multiple-output (mimo) wireless networks

An apparatus comprising at least one processor and at least one memory including computer instructions, when executed by the at least one processor, cause the apparatus to:

• receive, by a user device from a base station, a number of correlation coefficients of a correlation matrix to be reported to the base station, wherein the number of correlation coefficients is a subset of all correlation coefficients of the correlation matrix;
• determine, based on the number, a subset of non-zero correlation coefficients that represent a correlation of base station transmit beams;
• and
• report, by the user device to the base station, the subset of non-zero correlation coefficients.

A method comprising:

• receiving, by a user device from a base station, a first reference signal via a plurality of base station transmit beams;
• selecting, based on the first reference signal received via the plurality of transmit beams, beam indices for a subset of correlation coefficients to be reported to the base station;
• receiving, by the user device from the base station, a second reference signal via a plurality of the transmit beams;
• determining, based on the selected beam indices, the subset of correlation coefficients of a correlation matrix based on the second reference signal received via each of the plurality of transmit beams;
• and
• reporting, by the user device to the base station, the subset of correlation coefficients.

An apparatus comprising at least one processor and at least one memory including computer instructions, when executed by the at least one processor, cause the apparatus to:

• receive, by a user device from a base station, a first reference signal via a plurality of base station transmit beams;
• select, based on the first reference signal received via the plurality of transmit beams, beam indices for a subset of correlation coefficients to be reported to the base station;
• receive, by the user device from the base station, a second reference signal via a plurality of the transmit beams;
• determine, based on the selected beam indices, the subset of correlation coefficients of a correlation matrix based on the second reference signal received via each of the plurality of transmit beams;
• and
• report, by the user device to the base station, the subset of correlation coefficients.

A method comprising:

• sending, by a base station to a user device, a first reference signal via a plurality of base station transmit beams;
• receiving, by the base station as measured by the user device based on the first reference signal, a measured power and a beam index associated with the first reference signal for each of a plurality of the transmit beams;
• sending, by the base station to a user device, a number of correlation coefficients of a correlation matrix to be reported to the base station;
• sending, by the base station, a second reference signal via a plurality of the base station transmit beams;
• and
• receiving, by the base station from the user device, a subset of non-zero correlation coefficients of a correlation matrix based on the second reference signal.

An apparatus comprising at least one processor and at least one memory including computer instructions, when executed by the at least one processor, cause the apparatus to:

• send, by a base station to a user device, a first reference signal via a plurality of base station transmit beams;
• receive, by the base station as measured by the user device based on the first reference signal, a measured power and a beam index associated with the first reference signal for each of a plurality of the transmit beams;
• send, by the base station to a user device, a number of correlation coefficients of a correlation matrix to be reported to the base station;
• send, by the base station, a second reference signal via a plurality of the base station transmit beams;
• and
• receive, by the base station from the user device, a subset of non-zero correlation coefficients of a correlation matrix based on the second reference signal.