System and Method for Channel Information Feedback in a Wireless Communications System

A method for quantizing feedback information, the method comprising:

• receiving, by a communications device, a pilot transmitted by a controller;
• computing a channel estimate for a channel between the controller and the communications device using the received pilot;
• transforming the channel estimate into its representation in a subspace of the channel;
• quantizing the transformed channel estimate using a codebook, thereby producing an index to a codeword in the codebook, wherein all codewords in the codebook have a smaller dimensionality than a number of transmit antennas or antenna ports of the controller;
• transmitting, by the communications device, the index to the controller;
• and
• receiving, by the communications device, a transmission beamformed using the index and the subspace.

A communications device comprising:

• a receiver configured to receive a pilot signal;
• a channel estimate unit coupled to the receiver, the channel estimate unit configured to compute a channel estimate using the pilot signal for a channel between a controller and the communications device;
• a channel correlation matrix unit coupled to the channel estimate unit, the channel correlation matrix unit configured to compute a channel correlation matrix using the channel estimate;
• an adaptation unit coupled to the channel correlation matrix unit, the adaptation unit configured to adapt a first codebook using a reduced rank representation of the channel correlation matrix;
• a channel representation unit coupled to the adaptation unit, the channel representation unit configured to compute a representation of the channel;
• and
• a transmitter coupled to the channel correlation matrix unit, and to the channel representation unit, the transmitter configured to transmit the reduced rank representation of the channel correlation matrix as first feedback information and the representation of the channel as second feedback information, wherein the first feedback information occurs at a first rate in a time domain or is for a first bandwidth in a frequency domain, and the second feedback information occurs at a second rate in the time domain or is for a second bandwidth in the frequency domain, and wherein the first rate is lower than the second rate, and the first bandwidth is greater than the second bandwidth.