An example embodiment may involve defining a time-division multiplexed, orthogonal frequency-division multiplexed wireless air interface containing a primary signaling channel. The primary signaling channel may be formed by a first set of modulation symbols that are allocated to a fixed time position of each time-division multiplexed subframe across a plurality of contiguous subcarrier frequencies. A first set of the subcarrier frequencies may be powered at a first level and a second set of subcarrier frequencies may be powered at a second level. The example embodiment may also involve defining a secondary signaling channel. The secondary signaling channel may be formed in the air interface by a second set of modulation symbols that are allocated to dynamic time positions on the first set of the subcarrier frequencies. The example embodiment may further involve transmitting signaling messages to one or more WCDs via the secondary signaling channel.