Patent ID: 8750419

Claim:
A method for providing feedback for closed-loop transmitting with a plurality of transmit antenna elements and a plurality of receive antenna elements, the method comprising: providing a codebook containing sets of weightings for the plurality of transmit antenna elements with each set of weightings identified by an index and the codebook known to a transmitter and a receiver; pre-coding pilot signals using a precoding matrix to produce pre-coded pilot signals; transmitting the pre-coded pilot signals to the receiver via the plurality of transmit antenna elements; and in response to transmitting the pre-coded pilot signals, receiving at the transmitter an index to a set of weightings in the codebook for use in a subsequent transmission of a data stream wherein the set of weightings are based on a determined effective channel for a subset of rank 1 codebook weightings that produce ‘S’ effective channels and for each remaining codebook weightings as a low complexity function of the ‘S’ effective channels.