An adaptive modulation, coding and spreading (AMCS) transmitter is configured to map modulation symbols to a plurality of OFDM subcarriers to generate symbol-modulated subcarriers. For AMCS, some of the modulation symbols may be mapped to individual subcarriers (e.g., similar to conventional OFDM) and one or more of the modulation symbols may be mapped to (i.e., spread across) more than one of the subcarriers (i.e., unlike conventional OFDM) based on a spreading ratio. An IFFT may be performed on the symbol-modulated subcarriers prior to transmission. AMCS allows for adaptation to lower capacity and/or frequency-selective channels by optionally spreading existing modulations over multiple carriers and/or time slots. AMCS expands the catalog for possible modulations/codings by splitting a symbol across multiple carriers and/or time slots. AMCS is particularly useful when channel conditions are highly frequency-dependent or uniformly low capacity