A transmitter for transmitting data to communications devices via a wireless access. The transmitter including modulator circuitry configured to receive modulation symbols of a segment and to rotate each modulation symbol by an angle dependent on a choice of modulation scheme, and receive each of the segments of rotated modulation symbols and for each segment to separate real and imaginary components of the rotated modulation symbols for the segment and to interleave the real components of the rotated modulation symbols of the segment differently to the imaginary components of the rotated modulation symbols of the segment. The circuitry also is configured to re-combine the real and imaginary interleaved components of the rotated modulation symbols of each segment and to form from the real and imaginary components modulation cells.