Patent ID: 8406145

Claim:
A radio base station apparatus, having one or more groups including part or all of a plurality of remote radio units having one or more antennas, for transmitting a down link channel signal including control information that is the same for each group, a reference signal specifying a radio terminal, and user data to any radio terminal via the plurality of remote radio units, and receiving an up link channel signal from any radio terminal via the plurality of remote radio units, the radio base station comprising: an analysis section for calculating a correlation matrix R representing the degree of interference between each of two remote radio units based on a received signal; and a processing section for performing grouping; wherein the processing section checks the traffic on a control channel transmitted to each terminal, and obtains a total traffic Ti on the control channel for each remote radio unit i; the processing section transforms the correlation matrix R calculated in the analysis section to a partial orthogonal matrix R′ subjected to partial orthogonalization; the processing section divides the remote radio units into the groups including the one or more remote radio units in accordance with the partial orthogonal matrix R′; the processing section stores the identification number of the one or more remote radio units for each group in a memory, for performing the grouping; the processing section divides the remote radio units into a plurality of group candidates based on the diagonal elements of the partial orthogonal matrix R′, and adds the total of traffic on the control channel for one or more remote radio units included in each divided group candidate to obtain the total traffic for each group candidate, the processing section compares the obtained total traffic for each group candidate with the predetermined threshold, and if the obtained total traffic is greater than or equal to the threshold, the processing section performs the grouping by further dividing the group candidate so that the total traffic may be smaller than the threshold.