Systems for contention-based bandwidth requests in orthogonal frequency division multiplexing (OFDM) systems are provided. In one embodiment, a bi-directional communication system comprises: a multipoint-to-point host unit; and a plurality of remote units communicatively coupled to the multipoint-to-point host unit through an OFDM waveform. The multipoint-to-point host unit is configured to receive the OFDM waveform, the OFDM comprising a plurality of tones transmitted by the plurality of remote units. A first remote unit of the plurality of remote units is configured to transmit a request for bandwidth to the host unit on a tone of the plurality of tones, wherein access to the tone is contention-based. The multipoint-to-point host unit is configured to direct a modem to transmit information on at least one tone of the OFDM waveform based on whether the modem successfully receives the request for bandwidth from the first remote unit of the plurality of remote units.