On the Mode Switching of Reconfigurable-Antenna-Based Blind Interference Alignment

This paper reconsiders the design of blind interference alignment (BIA) for K-user MISO interference channel in which each receiver is equipped with a reconfigurable antenna of preset M
_k
≥ 3 modes. Beyond the degree of freedom (DoF)oriented BIA (D-BIA) design proposed by Lu etal., we further take into account the frequency of mode switching within one supersymbol frame. Even though every receiving antenna is reconfigurable with preset multiple modes, from an engineering perspective, it is of practical importance for each receiving antenna to make less number of mode switching in order to gain the benefits such as less switching power consumption and less signal distortion. To this end, we propose in this paper switching-oriented BIA (S-BIA) scheme, which preserves the same degree of freedom (DoF) gain as D-BIA while offering reduced mode switching frequency. Theoretical analysis and simulation results demonstrate that, compared to D-BIA, S-BIA can gain 100/(M - 1) percent of switching saving when M
_k
= M is odd for all transmitters. Remarkably, S-BIA offers 50% switching saving for multiuser 3 × 1 interference channels.