A processing unit generates the timing information on the timing with which each of radio apparatuses is to synchronize in communications between the radio apparatuses when each of radio apparatuses broadcasts a signal. A modem unit, an RF unit and an antenna broadcast the generated timing information. The processing unit further generates the cycle information on a broadcast cycle in which each radio apparatus broadcasts the signal in communication between the radio apparatuses. The modem unit, the RF unit and the antenna broadcast the cycle information together with the timing information.