A data processing apparatus to map input data symbols to be communicated onto a predetermined number of sub-carrier signals of Orthogonal Frequency Division Multiplexed OFDM symbols. The predetermined number of sub-carrier signals is determined in accordance with one of a plurality of operating modes and the input data symbols include first sets of data symbols and second sets of input data symbols. The data processing apparatus includes a controller, an address generator, and an interleaver memory. The controller is configured, when operating in accordance with an even interleaving process, to read out a first set of the input data symbols from the interleaver memory on to the sub-carrier signals of an even OFDM symbol using read addresses generated by the address generator, and to write in a second set of the input data symbols into the interleaver memory using the addresses generated by the address generator.