Patent ID: 8170092

Claim:
A data processing apparatus configured to map data symbols received from sub-carrier signals of Orthogonal Frequency Division Multiplexed (OFDM) symbols into an output data stream, the number of sub-carrier signals available for each OFDM symbol being variable between each of the OFDM symbols, and the data symbols including first sets of input data symbols and second sets of input data symbols received from odd and even OFDM symbols respectively, the data processing apparatus comprising: an address generator, a de-interleaver memory, and a controller, the controller being configured in combination with the address generator to de-interleave the first sets of data symbols and the second sets of data symbols by writing the first and second sets of data symbols into the de-interleaver memory and reading the first and second sets of data symbols out from the de-interleaver memory, the reading out of the de-interleaver memory being in a different order to the writing into the de-interleaver memory, the de-interleaving of the first sets of input data symbols being in accordance with an odd de-interleaving process including writing a first set of data symbols into the de-interleaver memory in accordance with addresses generated by the address generator, which have been received from an odd OFDM symbol; and reading out the first set of data symbols from the de-interleaver memory into the output data stream in a sequential order, and the de-interleaving of the second sets of data symbols being in accordance with the odd de-interleaving process including writing a second set of data symbols into the de-interleaver memory in accordance with addresses generated by the address generator, which have been received from an even OFDM symbol; and reading out the second set of data symbols from the de-interleaver memory into the output data stream in a sequential order of addresses, wherein the number of the sub-carriers which are available from a previous OFDM symbol is different from the number of the sub-carriers which are available from a current OFDM symbol, and the controller is configured to determine before writing the first data symbols into the de-interleaver memory, whether the write address is valid for the previous OFDM symbol; and to determine before writing the second data symbols into the de-interleaver memory, whether the write address is valid for the current OFDM symbol.