Apparatus and method for channel feedback in multiple input multiple output system

An apparatus for feeding a channel back to a transmitter in a multiple input multiple output (MIMO) system, the apparatus comprising:

• a channel estimator configured to:
• receive a signal from the transmitter, and
• configure a channel matrix for the received signal;
• a basis transformer configured to configure a basis transformed sparse channel using a sparsifying basis function with respect to the channel matrix, the transformed sparse channel being divided into a dominant part and a non-dominant part;
• a channel dimension reducer configured to select a channel part to be fed back to the transmitter from the dominant part of the transformed sparse channel based on a channel compression;
• and
• a channel quantizer configured to:
• create a codebook by quantizing the selected channel part, and
• feed a codebook index corresponding to the created codebook back to the transmitter.

A method for receiving channel feedback by a transmitter from a receiver in a multiple input multiple output (MIMO) system, the method comprising:

• receiving a codebook index from a receiver;
• selecting a channel vector using the codebook index and a codebook;
• restoring the dimension of the selected channel vector;
• performing basis inverse transformation with the same sparsifying basis function as that applied in the receiver to restore the channel;
• vectorizing, by the receiver, an estimated channel matrix, and
• transforming, by the receiver, the vectorized channel into a sparse domain by multiplying the vectorized channel by a sparsifying basis function to separate dominant elements that contribute to the channel and non-dominant elements that do not contribute to the channel.

An apparatus for receiving channel feedback from a receiver in a multiple input multiple output (MIMO) system, the apparatus comprising:

• a codebook channel restorer configured to:
• receive a codebook index from a receiver, and
• select a channel vector using the codebook index and a codebook;
• a channel dimension restorer configured to restore the dimension of the selected channel vector;
• and
• a basis calculator and channel restorer configured to perform basis inverse transformation with the same sparsifying basis function as that applied in the receiver to restore the channel,
• wherein the receiver is configured to:
• vectorize an estimated channel matrix, and
• transform the vectorized channel into a sparse domain by multiplying the vectorized channel by a sparsifying basis function to separate dominant elements that contribute to the channel and non-dominant elements that do not contribute to the channel.