| 摘要 |
A data processing apparatus maps symbols received from a predetermined number of sub-carrier signals of Orthogonal Frequency Division Multiplexed (OFDM) symbols into an output symbol stream. The data processor includes an interleaver memory which reads-in the predetermined number of data symbols for mapping onto the OFDM sub-carrier signals. The interleaver memory reads-out the data symbols on to the OFDM sub-carriers to effect the mapping, the read-out being in a different order than the read-in, the order being determined from a set of addresses, with the effect that the data symbols are interleaved on to the sub-carrier signals. The set of addresses are generated from an address generator which comprises a linear feedback shift register and a permutation circuit. The linear feedback shift register has eleven register stages with a generator polynomial for the linear feedback shift register of R i ¹ 10 = R i - 1 ¹ 0 Š• R i - 1 ¹ 2 , and the permutation code forms, with an additional bit, a twelve bit address. The permutation code is changed from one OFDM symbol to another, thereby providing an improvement in interleaving the data symbols for a 4K operating mode of an OFDM modulated system such as a Digital Video Broadcasting (DVB) standard such as DVB-Terrestria12 (DVB-T2). This is because there is a reduced likelihood that successive data bits which are close in order in an input data stream are mapped onto the same sub-carrier of an OFDM symbol.
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