Channel aided interference alignment

Interference alignment (IA) techniques mostly attain their degrees of freedom benefits as the number of channel extensions tends to infinity. Intuitively, the more interfering signals that need to be aligned, the larger the number of dimensions needed to align them. This requirement poses a major challenge for IA in practical systems. This study evaluates the necessary and sufficient conditions on channel structure of a fully connected interference network with time-varying fading to make perfect IA feasible within limited number of channel extensions. The authors propose a method based on the obtained conditions on the channel structure to achieve perfect IA. For the case of 3 user interference channel, it is shown that only one condition on the channel coefficients is required to make perfect IA feasible at all receivers. IA feasibility literatures have mainly focused on network topology so far, in contrast, derived channel aiding conditions in this study can be considered as the perfect IA feasibility conditions on the channel structure.