•Noise can be caused by electronic devices and radio transmitters.
•Path-loss occurs as the strength of the received signal steadily decreases in proportion to the distance from the transmitter.
•Shadowing is a form of environmental attenuation of radio signals caused by hills, buildings, trees or even vehicles. This can be a particular problem inside buildings, especially if the walls are thick and reinforced.
•Multi-path fading is a sudden decrease or increase in the signal strength. This is the result of interference caused when direct and reflected signals reach the antenna simultaneously. Surfaces such as buildings, streets, vehicles, etc., can reflect signals.
