According to an aspect, a transmitting device determines, for each of a plurality of transmissions, whether user data to be transmitted within a time transmission interval, TTT, will be closest in time to a DMRS transmitted before the user data or after the user data. If before the user data, all HARQ ACK/NACK data for the transmission is mapped to the earliest in time SC-FDMA symbol carrying user data in the transmission, and to pre-DFT symbols closest in time to the DMRS transmitted before the user data. If after the user data, all HARQ ACK/NACK data for the transmission is mapped to the last in time SC-FDMA symbol carrying user data in the transmission, and to pre-DFT symbols closest in time to the DMRS transmitted after the user data. SC-FDMA signals are formed from user data and control information for the transmission, based on the mapping.