Patent ID: 7844016

Claim:
A radio transmitting apparatus including a plurality of antenna elements, which is operable according to a multicarrier transmission process using a plurality of subcarriers, comprising: a calibration reference signal generator for generating a calibration reference signal for each of the subcarriers to be calibrated for equalizing amplitude characteristics and phase characteristics of radio transmitters, that correspond to the antenna elements for each of the subcarrier, to predetermined reference values; a subcarrier modulator for modulating the calibration reference signal generated by said calibration reference signal generator, with the subcarriers; a radio transmitter for frequency-converting a baseband signal, which is the modulated signal output from said subcarrier modulator, into a transmission signal in a radio frequency band; a radio receiver for frequency-converting the transmission signal in the radio frequency band, supplied from said radio transmitter to said antenna elements, into a baseband signal; a calibration coefficient measurer for calculating a calibration coefficient from the baseband signal output from said radio receiver; and a calibration coefficient multiplier for multiplying a transmission signal for each of said subcarriers and each of said antenna elements, by the calibration coefficient calculated by said calibration coefficient measurer, wherein said calibration reference signal generator comprises, a calibration subcarrier selector for generating a calibration reference signal corresponding to a subcarrier to be calibrated, and a calibration reference signal switcher for selecting either a calibration reference signal supplied from said calibration subcarrier selector or transmission data supplied from said calibration coefficient multiplier at a predetermined time, and for outputting the selected calibration reference signal or transmission data to said subcarrier modulator, and wherein said calibration reference signal generator changes a period for outputting said calibration reference signal with which to start calibrating each of the subcarriers when each of the subcarriers is to be calibrated a plurality of times.