Dual-polarized very large antenna array with exponential correlation matrix

Using large number of antennas at base station (BS) to formulate a multi-user multiple-input multiple-output (MU-MIMO) system, i.e., the massive MIMO, has attracted more and more attention recently, due to the high spectrum and energy efficiency it has. When there is correlation and mutual coupling, Rusek et al. showed that the channel may lose asymptotic orthogonality as the number of antennas increases. In this paper, we investigate the dual-polarized (DP) antenna array with exponential correlation and coupling model and prove that under the assumption that the correlation and coupling decreases exponentially with the distance between the antennas, the channels are still asymptotically orthogonal and we still have the same massive MIMO effect with the single-polarized (SP) antenna array. Through simulations, the asymptotic expressions are verified and the benefits brought by DP antenna array in massive MIMO system are quantitatively shown for both uniform linear array (ULA) and uniform planar array (UPA) configurations.