Net degrees of freedom of decomposition schemes for the MIMO IC with delayed CSIT

Abstract

Most techniques designed for the multiple-input multiple-output (MIMO) Interference Channel (IC) require accurate current channel state information at the transmitter (CSIT) which is not a realistic assumption because of feedback delay. We evaluate the net degrees of freedom (DoF) that different schemes can be expected to reach in a realistic system by taking into account the time and the cost of CSIT acquisition (training and feedback). A recent variant of ergodic interference alignment (IA) clearly outperforms the other schemes as its robustness to feedback delays proves to be advantageous in terms of net DoF.