| 摘要 |
A data transmission system employs an iterative decoder that applies decision feedback equalization (DFE) to channel output samples of a packet of data. The iterative decoder receives a stream of channel output samples as packets that may, for example, be read from a sector of a recording medium. Each packet may represent user data encoded, for example, with a concatenated code formed from N component codes, N a positive integer. The iterative decoder employs I decoding iterations, I a positive integer. DFE employs two filters: a feedforward filter and a feedback filter. The feedforward filter, which may be a whitened-matched filter used for detection, shifts dispersed channel output energy into the current sample. The feedback filter cancels energy of trailing inter-symbol interference from previous symbols. In each iteration by the iterative decoder, the DFE is applied to channel output samples of a packet by filtering with the feedforward filter, and then filtering with the feedback filter to cancel interference energy in the current sample from previous samples. The feedback filter uses soft information corresponding to tentative decisions for decoded data of the packet. During the first iteration, the soft information for applying DFE to the current sample is derived from the slicer output directly, and during the second and subsequent iterations the soft data of the decoder is provided to the feedback filter of the equalizer as soft information.
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