This lecture discusses the three multipath propagation mechanisms:

• Reflection
• Scattering
• Diffraction

We also consider propagation delay and delay spread, which increase in line with the transmission distance. Delay spread can be thought of like trying to have a conversation in an echoey room.

The lecture also discusses the behaviour of radio signals in buildings (indoor propagation). This depends on the working frequency, number of walls, ceilings, and other obstacles existing in a building. The indoor radio channel differs from the traditional mobile radio channel in two aspects:

• Distances covered are smaller
• Variability of the environment is much greater