A Simple Approach to Practical Dirty Paper Coding

This paper presents a simple dirty paper coding (DPC) scheme based on q-ary codes over integer rings. The encoding primarily involves a linear subtraction in the integer ring, for pre-cancellation of interference known at the transmitter. The received signal sequence corrupted by the interference is then guaranteed to belong to the expanded codebook of the ring code. As such, iterative q-ary message passing algorithm over the expanded codebook is employed for decoding of linear DPC, yielding near-capacity performance at the medium-to-high SNR regime for bandwidth efficient communication. The complexity of the proposed linear DPC is almost identical to that of the conventional coding for AWGN channel, and the power penalty is shown to quickly vanish as q increases. We employ a generalize EXIT chart based technique to optimize the degree distributions of the components and the multipliers of the underlying doubly irregular repeat-accumulate ring codes. Numerical results demonstrate that the gaps to capacity limit of the interference-free AWGN channel are only 1.36, 0.91, 0.62 dB for spectral efficiency of 2.0, 2.5, 3.0 bits/symbol, respectively.