Implement Blind Interference Alignment over Homogeneous 3-user 2x1 Broadcast Channel

This paper first studies the homogeneous 3-user 2×1 broadcast channel (BC) with no CSIT. We show a sufficient condition for it to achieve the optimal 3 2 degrees of freedom (DoF) by using Blind Interference Alignment (BIA). BIA refers to the interference alignment method without the need of CSIT. It further studies the 2×1 broadcast network in which there are K ≥ 3 homogeneous single-antenna users, and their coherence time offsets are independently and uniformly distributed. We show that, if K ≥ 11, the two-antenna transmitter can find, with more than 95% certainty, three users to form a BIA-feasible 3-user BC and achieve the optimal 3 2 DoF. Index Terms Blind interference alignment, DoF, homogeneous fading channel, MISO BC.