3-Dimensional channel characteristics on 2-dimensional active array antennas

Geometry-based stochastic channel models have been developed and refined over time by a number of research groups such as 3GPP, 3GPP2, ITU and the WINNER initiative. Traditional channel model is a two-dimensional (2-D) channel model, where an elevation angle of each signal path is always assumed to be zero. While such an approach is acceptable for evaluating performance of systems with horizontally placed linear antenna arrays, modeling of elevation angles is necessary when evaluating a massive MIMO or FD-MIMO technology utilizing a 2-D antenna array. In 3GPP, a study has been finalized the details and the following key parameters are takes into account the wireless channel propagation in the elevation direction as well as the azimuth direction; height dependent pathloss generation, correlation of large scale parameters, and statistical distribution of elevation components. This paper discusses spatial channel characteristics of vertical domain as well as horizontal domain under different 2-D active array configuration. Impact on separate and full channel measurement and feedback for horizontal and vertical antennas also discusses. Furthermore, we recommend the design principle of codebook for 2-D active array which impacts on system performance.