Degrees of freedom for K-user SISO interference channels with blind interference alignment

We derive the degrees of freedom (DoF) for K-user single-input single-output interference channels with a reconfigurable antenna at receivers, assuming linear coding strategies without channel state information at transmitters. Our DoF converse builds upon the inherent feature that channel state´s changing patterns of the links towards the same receiver are always identical. We prove the linear sum DoF is upper-bounded by n* K/K+n*(n*-1), n* where n* is the optimal number of preset modes among N. Moreover, we propose a linear scheme that achieves the upper-bound if K/n* is an integer. For the other cases, we give a guideline for the achievable scheme.