Opportunistic Interference Alignment by Receiver Selection in a K-User 1x3 SIMO Interference Channel

In this paper, we show that opportunistic interference alignment (OIA) by receiver selection achieves a total K degrees of freedom (DoF) in a K-user 1 × 3 single-input multiple-output (SIMO) interference channel (IC) when the number of receive antennas is three (N_R=3) at each receiver. The concept of OIA is geometrically interpreted on the complex unit sphere when the number of interferers is larger than N_R, i.e., K ≥ 4. We prove that OIA achieves DoF of one if the number of receivers associated with each transmitter increases with P_I^K-3 where P_I is the average power of each interferer.