Interference alignment scheme for downlink multi-carrier MIMO cellular systems

In this paperwe propose a practical interference alignment (IA) scheme for the downlink cellular systems with multi-carrier transmission over multi-input-multi-output (MIMO) channels, where the interference is decompounded into two parts (inter-cell and intra-cell interference). IA is used to effectively mitigate inter-cell interferences, while the intra-cell interference is suppressed by subcarrier allocation so that some spatial degrees of freedom are released. Assuming L Base stations each with M antennas and K users (having N antennas), we present that a necessary condition for zero inter-cell interference is (L-N)K ≤ M-1. In contrast, for a single-carrier MIMO cellular networks, the corresponding condition is known to be N + M ≥ LK + 1, which does not hold usually. An iterative optimization algorithm for the proposed scheme is given, and numerical results show that the proposed scheme achieves a high spectral efficiency when the number of users is large and the number of transmit and receive antennas is limited. © 2014 Binary Information Press.