Multipath Propagation

As Figure below illustrates, transmitted signals can combine with reflected ones to corrupt the signal detected by the receiver. This is known as multipath propagation. Delay spread is the amount of delay experienced by the reflected signals compared to the primary signal. As delay spread increases, the signal at the receiver becomes more distorted and possibly undetectable even when the transmitter and receiver are within close range.

Multipath propagation can be a significant problem, especially with indoor applications. Office furniture, walls, and machinery are obstacles that can redirect parts of the transmitted signal. Wireless LAN manufacturers compensate for the effects of multipath propagation by using special processing techniques. As examples, equalization and antenna diversity are methods for reducing the number of problems arising from multipath propagation.