On Blind Interference Alignment over Homogeneous Block Fading Channels

We examine how to construct blind interference alignment (BIA) in a K-user 2 × 1 broadcast network with homogeneous block fading, which means all users experience independent but identical block fading. When K=2, we determine a sufficient condition on the offset between the two users' fading blocks such that the constructed BIA achieves the optimal 4/3 degrees of freedom (DoF). Furthermore, we prove that, when K≥ 4, it is almost guaranteed that the transmitter can find two users among the K users to form a 2-user 2 × 1 broadcast channel over which BIA achieves 4/3 DoF.