Multipath

Multipath is the arrival of a transmitted signal at a receive antenna from multiple paths due to reflections. The reflections can occur from the ground, trees, buildings, people, or whatever is around. As an example, see Figure 1. The dominant signal is often the Line of Sight (LOS) signal, which is the direct path from the receiver to the transmitter. The other arriving signals (due to reflections) are known as multipath. In some situations (particularly in urban environments), there is no line of sight signal, and all received rays are from multipath. Multipath causes significant variation in received signal - sometimes the multipath reinforces the received signal, but often it subtracts from it (a phenomenon known as fading). See also diversity reception.