In one aspect, a transmitter, for a first time interval, allocates first and second portions of a frequency band to first and second multicarrier modulation schemes with first and second subcarrier spacings that differ from one another. The data is transmitted to wireless devices in the first time interval using the first and second multicarrier modulation schemes in the first and second portions of the frequency band. For a second time interval, third and fourth non-overlapping portions of a frequency band are allocated to third and fourth multicarrier modulation schemes that have third and fourth subcarrier spacings that differ from one another. The third and fourth portions and/or schemes differ from the first and second portions and/or schemes. The data is transmitted in the second time interval using the third and fourth multicarrier modulation schemes in the third and fourth portions of the frequency band.