Energy efficiency in multi-cell MIMO broadcast channels with interference alignment

Characterizing the fundamental metric of energy efficiency (EE) of multiple-input multiple-output interfering broadcast channels (MIMO-IFBC) is important for the development of green wireless communications. In this paper, we address the EE optimization problem for multi-cell MIMO-IFBC within the context of interference alignment (IA). We employ grouping-based IA scheme to cancel both inter-cell interference (ICI) and inter-user inference (IUI), and thus transform the MIMO-IFBC to a single cell single user MIMO scenario. A gradient-based optimal power adaptation scheme is proposed which utilizes water-filling approach and singular value decomposition (SVD) to maximize EE for each cell. Simulation results confirm the theoretical findings and demonstrate that the proposed resource allocation algorithm can efficiently approach the optimal EE.