A short-range radio transmitter of a communication device comprising a short-range radio and a long-range radio is controlled to delay packets which are scheduled to be transmitted at the same time as a long-range transmitter of the long-range radio commences or discontinues to transmit. A frequency synthesizer of the short-range radio is thereby not affected by a change in the power supply voltage which otherwise occurs at these moments due to transmission with high power by the long-range transmitter.