چكيده به لاتين
Due to the daily increase of communication networks usage, providing higher data rates and capacity gain more
and more important in the next cellular networks. One of the tools that have been proposed recently is the Massive
MIMO systems. However, for meeting the expected increase in the rate and capacity of the networks, it seems that
the only increase in the number of antennas is not sufficient and mmWave systems will be used beside them.
In this thesis, by leveraging tools from stochastic geometry, we investigated the effect of the height and 3Dbeamforming (3DBF) (tilt angle adjustment) on the energy efficiency (EE) and coverage in the Massive MIMO
systems. First, we studied the effect of the misalignment in the mmWave systems and observed that by using
base station cooperation, performance similar to alignment assumption can be achieved. Then, we investigated
the 3DBF enabled mmWave system in two scenarios of homogeneous and two-tier heterogeneous networks. It is
observed that optimizing the tilt angle both scenarios is complicated and a low complex near optimal approach
has been proposed for optimizing the EE in both scenarios. Afterwards, we studied the effect of the 3DBF on the
performance by considering variable user heights. To do so, we considered a massive MIMO system with pilot
contamination. It is observed that considering the users height and optimizing the tilt angle result in significant
performance improvement and ignoring the users height results in performance degradation even with respect to
2D-beamforming.
Afterwards, in a mmWave system by considering variable users height and 3DBF, we investigated the tilt angle
optimization for improvement of the performance by considering different small and large scale fading for LOS
and NLOS links. An effective low complexity approach has been introduced for finding the optimal tilt angle is
proposed.
Finally, since the meta distribution provides more comprehensive information about the performance of the
network, in Poisson bipolar and cellular networks, we studied the effect of the height on the important moments. It
is observed that as the height increases, the link reliability decreases.
