A non-implantable communication unit conducts wireless communication with an implantable medical device (IMD). The communication unit comprises a request processor for generating power down requests destined to the IMD and triggering temporary power down of the IMD radio equipment. When the communication unit receives a data packet from the IMD or a connected programmer it determines the size of the data packet. A timer processor sets a timer to a value defined based on the determined size. A processor controller selectively controls the operation of request processor to generate or stop generating the power down requests based on a current value of the timer. Power down of the IMD radio equipment is thereby prevented if it is likely that the IMD comprises data to transmit to the communication unit as predicted based on data packet sizes.
