Discrete Modulation for Interference Mitigation

• Published in: IEEE transactions on information theory Vol. 66; no. 5; pp. 3026 - 3039
• Main Authors: Baig, Mirza Uzair, Host-Madsen, Anders, Nosratinia, Aria
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.05.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Alignment; AWGN channels; Channels; Codes; Decoding; differential entropy bound; discrete modulation; Entropy; Interference; Interference channels; Modulation; Signal to noise ratio
• ISSN: 0018-9448; 1557-9654
• DOI: 10.1109/TIT.2019.2953916

This paper analyzes the performance of discrete input distributions (coded modulation) in interference channels. This approach is motivated in part by the necessity of using coded modulation in practical systems, and in part by the potential of discrete distributions for interference alignment as well as the importance demonstrated by Dytso et al. of discrete input distributions for transmission over the <inline-formula> <tex-math notation="LaTeX">2\times 2 </tex-math></inline-formula> interference channel when treating interference as noise. The contribution of this work includes the establishment of achievable rates subject to discrete modulations. In the process, new bounds involving the minimum distance of the sum of discrete modulations have been developed that are useful for facilitating further work in this area. These bounds are then used for finding achievable rates for <inline-formula> <tex-math notation="LaTeX">3\times 3 </tex-math></inline-formula> interference channels. It is also shown that interference alignment can be efficiently employed with discrete modulations at finite SNR even with imperfect channel state information at the transmitter.