Link Adaptation & Recursive Estimation for GPRS Wireless Networks
In most of the mobile or cellular systems, the height of the mobile antenna may be much lower than the surrounding structures. Thus, the existence of a direct or line of sight path between the transmitter and the receiver is highly unlikely. In such a case, propagation is mainly due to reflection and scattering from the buildings and by diffraction over and/or around them. So, in practice, the transmitted signal arrives at the receiver via several paths with different time delays creating a multipath situation at the receiver, these multipath waves with randomly distributed amplitudes and phases combine to give a resultant signal that Fluctuates in time and space. The phenomenon of random fluctuations in the received signal level is termed as fading.