Systems/methods are disclosed wherein, responsive to a size of data that is to be transmitted to a device, responsive to at least one other parameter and/or responsive to receiving instructions from the device, wirelessly transmitting to the device, over first, second, third and/or fourth non-overlapping intervals of time, respective first, second, third and/or fourth pluralities of subcarriers using respective first, second, third and/or fourth sets of frequencies; and further using respective first, second, third and/or fourth air interfaces that differ from one another in a physical layer aspect thereof. Systems/methods of wirelessly receiving from the device in ways analogous to said wirelessly transmitting to the device are also disclosed.