  Channel estimation is always implemented in communication systems to overcome
the effect of interference and noise. Especially, in wireless communications,
this task is more challenging to improve system performance while saving
resources. This paper focuses on investigating the impact of geometries of
antenna arrays on the performance of structured channel estimation in massive
MIMO-OFDM systems. We use Cram'er Rao Bound to analyze errors in two methods,
i.e., training-based and semi-blind-based channel estimations. The simulation
results show that the latter gets significantly better performance than the
former. Besides, the system with Uniform Cylindrical Array outperforms the
traditional Uniform Linear Array one in both estimation methods.
