Patent ID: 7904116

Claim:
A base station apparatus, comprising: an examining unit which examines a radio wave environment on at least one of a plurality of frequency channels usable for communications; a selector which selects one frequency channel to be used for communications, based on an examination result by said examining unit; an execution unit which transmits signals from a plurality of antennas to a terminal apparatus using the one frequency channel selected by said selector and which performs calibration on the plurality of antennas by receiving signals from the terminal apparatus by the plurality of antennas; and a storage unit which stores, in an associated manner, a result of calibration, executed in said execution unit, in the one frequency channel selected by said selector and a number to identify a frequency channel used for calibration, wherein the signal from the terminal apparatus received by the execution unit includes a first known signal for automatic gain control (AGC) estimation provided in at least one of a plurality of streams, a second known signal for channel estimation provided posterior to the first known signal in a plurality of streams, and data provided posterior to the second known signal in the same stream as the first known signal, the number of streams provided with the data is smaller than the number of streams provided with the second known signal, and at the time of execution of calibration said execution unit refers to the result of calibration and the number to identify a frequency channel, which are stored in said storage unit.