Per-User Unitary Rate Control (PU<sup>2</sup>RC) is a practical multi-user [[MIMO]] solution. PU2RCPU<sup>2</sup>RC allows a base station to transmit different data streams to multiple users simultaneously. The base station selects the target users among allfrom candidate users based on the information fed by users. DataTransmission transmitted to mobile usersdata are multiplied by a pre-coding matrix selected from the set of predefined matrices before transmission. The selection of a pre-coding matrix is madedetermined based on the information provided by users. The selection of both target users and a pre-coding matrix usingaccording to the information provided by mobiles enables the utilization of multi-user diversity and data multiplexing at the same time. Moreover. Using predefined precoding matrices reduces feedback overhead from users to the base station. Pre-coding matrices used in this scheme is unitary. The use of unitary pre-coding matrices facilitates the estimation of interference from other users’ data to the unintended user.
