Lattice precoding and pre-distorted constellation in degraded broadcast channel with finite input alphabets

In this letter, we propose a novel transmission scheme based on lattice precoding and pre-distorted constellation for the two-user AWGN degraded broadcast channel. In the proposed scheme, the lattice precoding is used for the weaker user to cancel the interference from the stronger user. The predistorted constellation is also proposed for the stronger user to overcome the nonlinear distortion due to the lattice precoding. Numerical results show that the achievable rate of the proposed transmission scheme is beyond the achievable rate region of the superposition coding and successive interference cancelation with finite input alphabets.