Abstract—Faster-than-Nyquist (FTN) signaling is known to maximize the number of signaling dimensions in point-to-point and certain multiuser channels. In this work, we show that these dimensions can be exploited by interference alignment to provide additional degrees-of-freedom (DoF) in interference channels. By employing FTN signaling using a modulating pulse with roll-off factor β > 0, each user in 3-user frequency-selective interference channel is shown to achieve (1+β)/2 DoF as the number of symbols tends to infinity, which is a (1+β)-folds gain from the conventional interference alignment with orthogonal signaling. We also highlight practically achievable DoF when the number of symbols is finite and the delay spread of the channel is limited.
Kim, Yong Jin Daniel and Vargas, David, "Can Additional Degrees-of-Freedom from Faster-than-Nyquist Signaling be Used to Align Interference? (TO BE SUBMITTED TO 2017 IEEE INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY)" (2017). Faculty Publications - Electrical and Computer Engineering. 1.