Ebook Free Download | WiMAX’s technology for LOS and NLOS environments | The radio channel of a wireless communication system is often described as being either LOS or NLOS. In a LOS link, a signal travels over a direct and unobstructed path from the transmitter to the receiver. A LOS link requires that most of the first Fresnel zone is free of any obstruction, if this criteria is not met then there is a significant reduction in signal strength. The Fresnel clearance required depends on the operating frequency and the distance between the transmitter and receiver locations.
In a NLOS link, a signal reaches the receiver through reflections, scattering, and diffractions. The signals arriving at the receiver consists of components from the direct path, multiple reflected paths, scattered energy, and diffracted propagation paths. These signals have different delay spreads, attenuation, polarizations, and stability relative to the direct path. continue reading…