Why does high-rise buildings require better RxLevel, in terms of mobile signal?

Question

e.g.
RxLevel for 2G High-rise buildings >= -70dBm.
RxLevel for 2G Low-rise buildings >= -80dBm.

How do we explain the above?

Answer 1

Hi rise buildings are usually loaded with metal reinforcements which attenuate the signal. Low rise buildings usually require less strengthening so there's less metal present.