Relay-aided interference alignment: Feasibility conditions and algorithm

Consider a (1 × 1,  )K symmetric wireless interference network where K single-antenna user-pairs want to achieve  degrees of freedom each. It has been proved that it is almost surely infeasible to achieve interference alignment without symbol extension. While it was proved relays can not increase the degree of freedom of wireless interference networks, we show this does not preclude the usefulness of using relays to construct practical solutions to approach interference alignment with finite symbol extensions. Feasibility conditions for relay-aided interference alignment are analyzed and an example about how to design the relaying functions to approach interference alignment is given. Simulation results also justify the use of relays as a practical means to do interference alignment with finite symbol extensions.