Interference alignment with imperfect channel state information at the transmitter

A novel interference alignment (IA) algorithm is presented. IA solutions can be obtained in closed-form for special cases only. In general, iterative algorithms need to be used. Most of these algorithms are based on a joint design of precoders at the transmitter side and receive filters at the receiver side, while the proposed method achieves IA with a precoder design only. A design based on precoders simplifies the problem structure and allows receive filters to be designed independently of the IA conditions. In case the channel state information at the transmitter side (CSIT) is not perfectly known, IA cannot be completely achieved and the calculated precoders will result in degradation of achievable rates. An adapted receive filter design can help counteract the rate degradation and improve achievable rates as compared to a non-adapted receive filter design. The proposed solution is a good trade-off between required CSIT and achievable rates, as compared to state-of-the-art methods.