Cognitive Blind Interference Alignment for Macro-Femto Networks

• Published in: IEEE transactions on signal processing Vol. 65; no. 19; pp. 5121 - 5136
• Main Authors: Morales-Cespedes, Maximo, Plata-Chaves, Jorge, Toumpakaris, Dimitris, Ali Jafar, Syed, Garcia Armada, Ana
• Format: Journal Article
• Language: English
• Published: IEEE 01.10.2017
• Subjects: Antenna radiation patterns; Blind interference alignment; Cellular networks; channel state information; degrees of freedom; Electronic mail; Femtocells; heterogeneous networks; Interference; reconfigurable antennas; Transmitters
• ISSN: 1053-587X; 1941-0476
• DOI: 10.1109/TSP.2017.2721912

We propose a cognitive blind interference alignment (BIA) scheme for macro-femto two-tier networks where the users are equipped with a single reconfigurable antenna. The proposed scheme fully cancels the intracell interference in both the upper and lower tiers. Moreover, it provides the optimal Degrees of Freedom (DoF) in the macro-tier while the lower tier subject to inter-tier interference achieves non-zero DoF. To do so, the proposed scheme relies on a topology management scheme where the users belong to the macro-tier if and only if they can optimally treat the interference caused by the transmission at the femto-tier as noise. The proposed scheme does not require any channel state information at the transmitter or data sharing between the macro- and femto-tiers. An outer bound of the DoF is derived for the considered macro-femto network. It is demonstrated that the proposed scheme can attain the outer bound subject to optimal sum DoF for the macro-tier. Furthermore, compared to previous approaches, cognitive BIA can achieve better sum rates for macro-femto networks for femtocells subject to different levels of inter-tier interference.