Methods and systems are provided for using frequency spreading during communications, in particular communications in which multiple carriers (or subcarriers) are used. The frequency spreading may comprise generating a plurality of spreading data vectors based on transmit data, such as by application of a spreading matrix to portions of the transmit data. Each spreading data vector may comprise a plurality of elements, for assignment to the multiple subcarriers. The receive-side device may then apply frequency de-spreading, to obtain the original transmit data. The frequency de-spreading may comprise use of the same spreading matrix on data extracted from received signals, which (the data) may correspond to the plurality of spreading data vectors.