Interference alignment and power allocation for the MIMO X channels with multiple layers of relays

Abstract

In this paper, we study a system consisting of a single source, a single destination, and multiple layers of parallel relays. The system is considered as a combination of broadcast channels, multiple input multiple output (MIMO) X channels, and multiple-access channels. Interference alignment (IA) is used throughout the whole system, and perfect channel state information (CSI) is assumed available at all the transmitters and receivers. Iterative algorithms are applied to find the proper transmit and receive matrices in the broadcast channels and multiple-access channels. For the MIMO X channels, based on IA technique, we design the transmit and receive beamforming matrices. Finally, in order to maximize the total transmission rate of the whole system, we optimize the power allocation of each transmitter.