US Patent 9172448 Base-station apparatus, terminal apparatus, communication system, and communication method

A base-station apparatus configures a terminal apparatus with information related to mapping between a first channel-state information reference signal and a second channel-state information reference signal and codebook subset restriction information that restricts selection of a codebook subset as feedback information by the terminal apparatus, the codebook subset indicating precoding a weight to perform a first communication and a second communication. Using the information related to the mapping and the codebook subset restriction information, the terminal apparatus selects a codebook to perform the first communication and a codebook to perform the second communication. The terminal apparatus configures the base-station apparatus with information indicating the codebook to perform the first communication and information indicating the codebook to perform the second communication.