Why does 5G mmWave require more cells

5 GHz networks do not penetrate solid objects such as walls nearly as well as do 2.4 GHz signals. This can limit an access points reach inside buildings like homes and offices where many walls may come between a wireless antenna and the user.

Blocking due to physical obstacles will be one of the biggest challenges for 5G affecting significantly indoor propagation. This is due to the materials used for building construction[7]. Other physical objects that can reduce the propagation of 5G are tree leaves and human body parts[8].19 Eyl 2019

“Trees are cut down because they block 5G signals and, in addition to this, more space is required for new transmitter antennas.” Trees, buildings, vehicles and even rain can influence how 5G signals propagate.