Massive MIMO with Dual-Polarized Antennas

This paper considers a single-cell massive MIMO (multiple-input multiple-output) system with dual-polarized antennas at both the base station and users. We study a channel model that takes into account several practical aspects that arise when utilizing dual-polarization, such as channel cross-polar discrimination (XPD) and cross-polar correlations (XPC) at the transmitter and receiver. We analyze uplink and downlink achievable spectral efficiencies (SE) with and without successive interference cancellation (SIC) for the linear minimum mean squared error (MMSE), zero-forcing (ZF), and maximum ratio (MR) combining/precoding schemes. In addition, we derive the statistical properties of the MMSE channel estimator for the dual-polarized channel model. These estimates are used to implement different precoding and combining schemes when the uplink and downlink SE expressions are calculated for the case. Closed-form uplink and downlink SE expressions for MR combining/precoding are derived. Based on these results, we also provide power control algorithms to maximize the uplink and downlink sum SEs. Moreover, we compare the SEs achieved in dual-polarized and uni-polarized setups numerically and evaluate the impact of XPD and XPC.