Method, apparatus and computer program product where a base station broadcasts a signal indicating that at least one time-frequency region, which is unused by a data transmission in a first radio access technology, is available for a transmission, allowing the base station to maintain support for and/or extending coverage of certain legacy user equipment. Such a transmission includes system information for a second radio access technology, wake-up signal, synchronization signal, and/or extension of the data transmission. Thereafter, the base station transmits such a transmission in the at least one time-frequency region that was indicated.