Optimization of Interference Alignment in MIMO Channel with Multiple Layers of Relays

We investigate a system consisting of a single source, a single destination and multiple layers of parallel relays. The system can be considered as a combination of a broadcast channel, a multi-user multiple input multiple output (MIMO) interference channel and a multiple access channel. Interference alignment (IA) scheme is used throughout the whole system and perfect channel state information (CSI) is assumed available at all transmitters and receivers. In this paper, we consider two layers of parallel relays and our objective is to optimize the power allocation of each transmitter to maximize the total transmission rate of the whole system. Iterative algorithms are derived to find the optimal precode and decode vectors.