A novel interference cancellation scheme with constellation alignment

This paper proposes a novel constellation alignment and interference cancellation scheme for wireless systems. Compared with the existing literatures on interference channel capacity analysis with lattice codes, a general signal processing algorithm is proposed for the systems using mutual baseband signal processing components, i.e., channel coding and QAM modulation. Specifically, multiple interference transmitters are proposed to align their QAM constellations at the signal receiver; the receiver first demodulates the aligned interference symbols by a novel constellation, then detects the aligned interference message which is the bitwise exclusive or of each individual interference message, and finally, cancels the aligned interference and detects the desired signal. Since the complicated joint detection in the existing lattice-based interference alignment literatures is avoided, the overall complexity is dramatically reduced. With the proposed scheme, the signal receiver can exploit both modulation and channel coding structure of interferences to improve the quality of interference cancellation. Hence, it is shown that compared with the existing wireless systems without constellation alignment, the proposed scheme could significantly improve the receiver´s performance in the scenario with multiple interference sources.