Systems for control modulation in multipoint-to-point communication using orthogonal frequency division multiplexing (OFDM) are provided. In one embodiment, a system comprises a host; a plurality of remote units using a multiple access scheme to communicate at the same time with the host using OFDM; wherein the host allocates orthogonal tones within the system to the plurality of remote units; wherein the host sends an adjustment signal to at least one of the remote units instructing the at least one remote unit to adjust the timing of transmissions from the remote unit to improve orthogonality of OFDM transmissions received at the host from the plurality of remote units; and wherein control data is sent between the host and at least one remote unit using a more robust modulation scheme than the modulation scheme used to send payload data between the host and the at least one remote unit.