Two novel iterative algorithms for interference alignment with symbol extensions in the MIMO interference channel

Interference alignment(IA) with symbol extensions in the K-user multiple-input multiple-output (MIMO) interference channel(IC) is considered in this paper. Symbol extensions produce the channels of special structure. Most of existing approaches are limited in cases where the channels have some special structure, because they align the interference without preserving the dimensionality of the desired signal. For that reason, two novel iterative algorithms for IA with symbol extensions are proposed. The first algorithm designs transceivers for IA based on minimizing the maximum per-user mean square error(MSE) while preserving the dimensionality of the desired signal. Utilizing channel reciprocity, the second algorithm is proposed which is the constrained optimization problem. It maximizes each receiver´s SINR while preserving the dimensionality of the desired signal. The simulation results show that the proposed algorithms not only achieve good performance in terms of BER performance but also achieve good performance on maximizing sum rate of the system.