To obviate complicated transmission power control in a mobile station.

A time slot (TS) allocation part 109 belonging to a base station 10 determines a time slot that allows communication for each of mobile stations 11 to 13 based on the magnitude of estimated value of a path loss, which is one of parameters that have a correlation with an inter-station distance (distance between stations) between the mobile stations 11 to 13. A reception gain control part 107 adjusts gain for upstream signal received from the mobile stations 11 to 13 for each time slot so that the signal level after amplification of the upstream signal transmitted by substantially constant transmission power from each of the mobile stations 11 to 13 falls within a predetermined dynamic range.