On the achievable capacity of dual-polarized antenna systems in 3D indoor scenarios

Unlike triple-polarized antennas, dual-polarized antennas can be easily implemented into thickness limited devices and thus have received much attention recently. Dual-polarized antennas have the potential to double the channel capacity in comparison with an omnidirectional single-input single-output (SISO) system. However, in real three-dimensional (3D) scenarios, dual-polarized antennas cannot capture the arriving power from the third polarization direction, which is orthogonal to the two-dimensional (2D) polarization plane. This will lead to power loss, which may significantly affect the resultant channel capacity. By proposing a novel two-sphere single-bounced geometry-based stochastic model (GBSM) and rigorously analyzing the change of polarization after single-bounced scattering, this paper studies the impact of the power loss on the channel capacity and specifies the conditions under which the channel capacity of dual-polarized systems is even worse than that of omnidirectional SISO systems. Not only that this is the first endeavor on this subject, but also this work is of practical importance in guiding appropriate deployment of dual-polarized antennas in real 3D indoor scenarios.