Patent ID: 8351544
Filing Date: 2013-01-08
Classification: H04B,H04L

Abstract:
1. 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 pre-coding pilot signals comprises pre-coding pilot signals using a unitary matrix and further, wherein the receiver is not informed, by the transmitter, of the unitary matrix used to pre-code the pilot pattern.