Performance of the blind interference alignment using ESPAR antennas

Recently, a technique entitled "Blind Interference Alignment (BIA)" was proposed, which allows interference alignment to be achieved without the knowledge of channel state information at the transmitter. The key to realizing the BIA scheme is the use of a receive antenna capable of switching among multiple beampatterns. The ESPAR antenna, which uses only a single RF front-end, is capable of forming different directional beampatterns by the use of circular permutations of the reactive loads of the passive elements. We introduce the ESPAR antenna as a potential solution for the practical implementation of the BIA for broadcast channel as well as cellular. The BIA scheme is accomplished by the transmission strategy jointly coordinating with the ESPAR beampattern switching symbol-wise. The ESPAR beampattern switching provides the necessary channel diversity for receiving users. Simulation results demonstrate that the ESPAR beam steering can be designed to improve the performance of the BIA scheme by enhancing the receive signal-to-noise ratio (SNR). Furthermore, we study the proposed BIA scheme for a simple 1-dimensional cellular setting to illustrate that the ESPAR beamforming can improve the performance of the cell-edge users through further suppressing the remaining inter-cell interference.