Complex sentence: In wireless systems, fading may either be due to multipath propagation, referred to as multipath induced fading, or due to shadowing from obstacles affecting the wave propagation, sometimes referred to as shadow fading.
Split into simpler sentences: In wireless systems, fading may be due to multipath propagation, referred to as multipath induced fading. In some contexts shadowing from obstacles affecting the wave propagation is referred to as shadow fading.