Explanation: Small scale fading or simply fading, is used to describe the rapid fluctuations of amplitudes, phases, or multipath delays of a radio signal over a short period of time or travel distance. It ignores the large scale path loss.

Explanation: Fading is caused by interference. It is caused by interference between two or more versions of the transmitted signal which arrive at the receiver at slightly different times.

Explanation: Rapid changes in signal strength over a small travel distance are caused due to multipath. It causes random frequency modulation due to varying Doppler shifts on different multipath signals. Time dispersion is also caused by multipath propagation delays.

Explanation: In urban areas, fading occurs because height of the mobile antenna is below the height of surrounding structures. Therefore, there is no single line of sight path to the base station.

Explanation: The received signal may fade even when the mobile receiver is stationary. It is due to the movement of surrounding objects in the radio channel. The multipath components combine vectorially at the receiver antenna and cause signal to distort or fade.

Explanation: Due to relative motion between mobile and base station, each multipath wave experiences an apparent shift in frequency. This shift in received signal frequency due to motion called Doppler shift.

Explanation: The shift in received signal frequency due to motion is called Doppler shift. It is directly proportional to the velocity and direction of motion of mobile with respect to the direction of arrival of the received multipath wave.

Explanation: Many physical factors in radio channel influence small scale fading. Multipath propagation, speed of mobile, speed of surrounding objects, transmission bandwidth of the signal influences small scale fading in a large way.

Explanation: Received signal will be distorted if transmitted signal bandwidth is greater than bandwidth of multipath channel. But received signal strength will not fade much over a local area.

Explanation: The bandwidth of the channel can be quantified by the coherence bandwidth. It is related to the specific multipath structure of channel. It is a measure of maximum frequency difference for which signals are strongly correlated in amplitude.

Explanation: Doppler shift is given by (v*cos θ)/λ. This formula relates the Doppler shift to the mobile velocity and spatial angle between the direction of motion of mobile and the direction of arrival of the wave.

Explanation: Doppler shift is positive if the mobile is moving toward the direction of arrival of the wave, as the apparent received frequency is increased. And if the mobile is moving away from the direction of arrival of the wave, Doppler shift is negative.