Feasibility conditions of interference alignment via two orthogonal subcarriers

Conditions are derived on the interference channel with single-antenna nodes to achieve maximal degrees-of-freedom with only two symbol extensions. The conditions for line-of-sight channels involve choosing only the spacing between two subcarriers of an orthogonal frequency division multiplexing (OFDM) scheme. For 3 user pairs an upper bound on the sum-rate of interference alignment is approached arbitrarily closely.