In a mobile network, the transmission of downlink data blocks to one or more terminal devices is accomplished on the basis of a retransmission protocol with a first feedback time defining a time interval between transmission of a first data block and transmission of a first feedback message being different from a second feedback time defining a time interval between transmission of a second data block and transmission of a second feedback message. The first feedback message indicates whether the first data block was successfully received, and the second feedback message indicates whether the second data block was successfully received. A base station of the mobile network controls the terminal device to send the second feedback message on other resources than used for transmission of the first feedback message.