Optimal multiplexing gain of K-user line-of-sight interference channels with polarization

We consider the multiplexing gain (MUXG) of the fully connected i¿i¿-user line-of-sight (LOS) interference channels (ICs). A polarimetric antenna composed of 3 orthogonal electric dipoles and 3 orthogonal magnetic dipoles is considered where all 6 dipoles are co-located. In case of K-user IC with single polarization, the maximum achievable MUXG is K regardless of the number of transmit and receive antennas because of the key-hole effect. With polarization, a trivial upper bound on the MUXG is 2K. We propose a zero forcing (ZF) scheme for the i¿i¿-user LOS IC, where each user uses one or more polarimetric antennas. By using the proposed ZF scheme, we find minimal antenna configurations that achieve this bound for K ¿ 5. For K > 5, we show that the optimal MUXG of 2K is achieved with M = [K + 1/6] polarimetric antennas at each user.