Welcome to the Institute of Digital Signal Processing!

Interference Alignment

Interference Alignment (IA) enables to linearly increase the sum rate with an increasing number of user pairs at high signal to noise ratio (SNR) and is therefore of an almost similar relevance for a wireless communication system as the bandwidth or the minimum number of transmit and receive antennas. IA applies to the interference channel, where several user pairs simultaneously communicate over the same portion of the radio spectrum, and requires the complete channel state information (CSI) at each user. The basic principle of IA is to linearly precode the transmit signals such that the interference signal at each receiver lies in a subspace with reduced dimension enabling the interference cancellation. One major challenge of IA is to increase its robustness, e.g., against channel imperfections or CSI estimation errors. DSV scientists have studied IA-related problems since 2009 with focus on understanding and increasing the robustness of IA. Special emphasis is given to optimizing such degrees of freedom caused by technological options, e.g. by including advanced antennas with orthogonal directivity patterns. As a successful example, we have applied antenna selection techniques to IA leading to significant robustness improvements in indoor environments.

In the future, DSV will focus on applying IA to cellular communication systems, in particular to future releases of LTE and its implementation on pre-commercial software configurable platforms.