Patent ID: 8326245

Claim:
A radio communication apparatus for transmitting a radio signal to multiple users via multiple transmit antenna groups at appropriate transmit power levels, each of the transmit antenna groups including one or more transmit antennas, the transmit antenna groups having respective transmit power constraints comprising: a precoding unit configured to perform precoding on signals modulated for individual users and generate transmit weights; an optimum transmit power calculation unit configured to receive the transmit weights from the precoding unit and use components of the transmit weights and respective transmit power limit values for the transmit antenna groups to calculate an initial value for a transmit power optimization problem for calculation of the appropriate transmit power levels for the users; and a transmission unit configured to transmit radio signals at the calculated transmit power levels, wherein the initial value is used to solve the transmit power optimization problem in an iterative manner in accordance with an interior point method, and wherein the initial value results from normalization of the respective transmit power limit values for the transmit antenna groups with a square sum of the components of the transmit weights.