Methods of transmitting a plurality of communications signals over a plurality of discontiguous bandwidth segments in a frequency band include defining a plurality (NFFT) of orthogonal subcarriers across the frequency band, defining a plurality (N) of available physical subcarriers from among the orthogonal subcarriers. The available physical subcarriers are distributed among, the plurality of discontiguous bandwidth segments. The methods further include spreading the data symbols for each user and combining the spread data symbols to provide composite data signals. The composite data signals are converted to parallel input signals and interleaved. The interleaved signals are assigned to the N available physical subcarriers. Related transmitters, receivers and communications systems are also disclosed.