Slepian-Wolf Coding of Binary Finite Memory Source Using Burrows-Wheeler Transform

Summary form only given: In all existing codec designs for asymmetric Slepian-Wolf coding (SWC), it is assumed that the source sequence is i.i.d and equiprobable. When it comes to more complex source statistics, the encoder should firstly remove the redundancy within the source. However, this increases the complexity of the encoder. In this paper, we propose an asymmetric SWC scheme which explores the redundancy of the binary finite memory source (FMS) at the decoder. Specifically, inspired by the Burrows-Wheeler transform (BWT)-based source-controlled channel decoding algorithm proposed, we iteratively apply the LDPC decoding and BWT to the side information. In our codec implementation, the encoder is identical to the conventional LDPC-based SWC encoder. At the decoder, conventional LDPC-based SWC decoding algorithm and Burrows-Wheeler transform (BWT) are iteratively applied to the side information for decoding. BWT can asymptotically permute a FMS into a piece-wise i.i.d binary sequence. In other words, by applying BWT to the decoder side information, the redundancy in the memory is transformed into the redundancy in the marginal distributions of the output i.i.d segments. The marginal distributions of every i.i.d segment can be used as the a priori information for SWC decoding. To explore the marginal distribution, a segmentation algorithm is employed to adaptively partition the output sequence of BWT into i.i.d segments. The bias parameter of each segment is then empirically computed. Using these parameters, the a priori information of the FMS source can be derived and incorporated in the next iteration of SWC decoding. Experimental results show that our scheme performs significantly better than the scheme which does not utilize the a priori information for decoding.