1. For a nonfading signal component present, the small scale fading envelope distribution is ____________
a) Rayleigh
b) Gaussian
c) Log normal
d) Ricean
Explanation: The small scale fading envelope is Ricean when there is a dominant stationary (nonfading) signal component, such as line of sight propagation path. In such a situation, random multipath components arriving at different angles are superimposed on a stationary dominant signal
2. Ricean distribution degenerates to ________ distribution when the dominant component fades away.
a) Log normal
b) Gamma
c) Rayleigh
d) Gaussian
Explanation: Ricean distribution degenerates to Rayleigh distribution when the dominant component fades away. As the dominant signal becomes weaker, the composite signal resembles a noise signal which has an envelope that is Rayleigh.
3. The envelope of a bandpass noise is __________
a) Uniformly distributed
b) Rayleigh
c) Ricean
d) Gaussian
Explanation:The envelope of only bandpass noise is Rayleigh distribution. Rayleigh distribution is a continuous probability density function for positive random variables.
4. The envelope of a sinusoid plus bandpass noise has __________
a) Uniformly distributed
b) Rayleigh
c) Ricean
d) Gaussian
Explanation: The envelope of a sinusoid plus bandpass noise has Ricean distribution. In probability theory, Ricean distribution is the probability distribution which has magnitude of a circular bivariate normal random variable with potentially non-zero mean.
5. What do you call an attenuation that occurs over many different wavelengths of the carrier?
a) Rayleigh fading
b) Ricean fading
c) Wavelength fading
d) Slow fading
Explanation: Slow fading does not vary quickly with the frequency. It originates due to effect of mobility. Slow fading is the result of signal path change due to shadowing and obstructions such as tree or buildings etc.
6. Which of the reception problems below that is not due to multipath?
a) Delayed spreading
b) Rayleigh fading
c) Random Doppler shift
d) Slow fading
Explanation: Slow fading arises when the coherence time of the channel is large relative to the delay requirement of the application. Slow fading is caused by events such as shadowing, where a large obstruction such as a hill or large building obscures the main signal path between the transmitter and the receiver
7. The term small scale fading describes the slow fluctuations of received power level due to changes in receiver position.
a) True
b) False
Explanation: The term small scale fading describes the rapid fluctuations of received power level due to changes in receiver position. This effect is due to the constructive and destructive interference of the numerous multipath waves that impinge upon a wireless receiver.
8. The rapid fluctuations due to small scale fading affect the _________ design.
a) Receiver
b) Transmitter
c) MSC
d) Base station
Explanation: The rapid fluctuation due to small scale fading affect every aspect of receiver design such as dynamic range, equalization, diversity, modulation scheme and channel error correction coding. These fluctuations are a function of direction of travel as related to the angle of arrival of multipath delay.
9. An approximately omnidirectional channel model accurately describes fading statistics if directional antennas are employed at the receiver.
a) True
b) False
Explanation: An approximately omnidirectional channel model accurately describes fading statistics if directional or smart antenna systems are employed at the receiver. Unfortunately, recent measurements and models have shown that the arriving multipath in a local area bears little resemblance to the omnidirectional propagation.
10. Which of the following is not a principle shape factor?
a) Angular spread
b) Angular constriction
c) Azimuthal direction of maximum fading
d) Angle of arrival
Explanation: Three principle shape factors are angular spread, angular constriction, and azimuthal direction of maximum fading. They are exactly related to the average rate at which a received signal fades.