3D channel model extensions and characteristics study for future wireless systems

This work introduces a complete framework for three-dimensional (3D) channel extension based on two-dimensional (2D) channel models. In the 3D channel modeling, besides the azimuth angles, the multipath components of a receive-transmit pair are determined by elevation angles, correlations between elevation and azimuth, and the 3D configurations of a user equipment´s (UE) location and velocity. The 3D channel characteristics for an active antenna system (AAS) are studied in terms of aggregated array gain and channel covariance matrix. The 3D channel model is generated and examined through Monte Carlo simulations and a comparison of fixed vertical beamforming and adaptive vertical beamforming is presented. The comparison shows that adaptive vertical beamforming can potentially provide up to 8dB improvement in coupling loss. In addition, it is shown that for line-of-sight (LoS) the 3D channel covariance matrix can be decoupled into two independent covariance matrices with reduced sizes that effectively leads to reduced feedback overhead. For non-line-of-sight (NLoS), the correlation-based Kronecker model technique can be used to generate the 3D channel matrix with reduced complexity compared to the geometry-based technique.