  Interference alignment(IA) is mostly achieved by coding interference over
multiple dimensions. Intuitively, the more interfering signals that need to be
aligned, the larger the number of dimensions needed to align them. This
dimensionality requirement poses a major challenge for IA in practical systems.
This work evaluates the necessary and sufficient conditions on channel
structure of a 3 user interference channel(IC) to make perfect IA feasible
within limited number of channel extensions. It is shown that if only one of
interfering channel coefficients can be designed to a specific value,
interference would be aligned perfectly at all receivers.
