A head end controller is described. The head end controller controls a plurality of service units in a telecommunications system with a multi-carrier transmission scheme. The head end controller includes a logic circuit that generates control messages for the plurality of service units. Each service unit is assigned to at least one subband of a transmission bandwidth. The head end controller further includes a transceiver that is coupled to a distribution network of the transmission system, wherein the transceiver broadcasts control messages to the plurality of service units. The plurality of service units are configured to use a multiple access scheme to transmit on a radio frequency carrier using orthogonal frequency division multiplexing (OFDM) so that transmissions from the plurality of service unit are received from the distribution network at the transceiver synchronized within an OFDM waveform.