ABSTRACT
Propagation of signals through wireless channels (indoors or outdoors) results in the transmitted signal arriving at the receiver through multiple paths. ese paths arise due to reection, refraction, or diraction in the channel. Multipath propagation results in a received signal that is a superposition of several delayed and scaled copies of the transmitted signal giving rise to frequency-selective fading. Frequency-selective fading (dened as changes in the received signal level in time) is caused by destructive interference among multiple propagation paths. e environment around the transmitter and the receiver can change over time, particularly in a mobile setting, leading to variations
2.1 Introduction ............................................................ 35 2.2 Wireless Channel Models ...................................... 36
2.6 Conclusions..............................................................66 Acknowledgment ............................................................... 67 References ........................................................................... 67
in the channel response with time. is gives rise to time-selective fading. Also, the channels may have a dominant path (direct path in line-of-sight channels) in addition to several secondary paths, or they may be characterized as having multiple “random” paths with no single dominant path.
