Fading Effect in Wireless Communication MCQ [Free PDF]

1. Fading channel has memory.

A. True
B. False

Answer: A

The fading channel has memory and the received samples are correlated with each other in time.

 

2. How can frequency selective distortion be minimized?

A. By using the pilot signal
B. By adaptive equalization
C. By spread the spectrum
D. All of the mentioned

Answer: D

Frequency selective distortion can be minimized by using adaptive equalization, using spread spectrum, by using pilot signal, and also by using orthogonal FDM modulation.

 

3. How can slow fading be minimized?

A. By diversity technique
B. Error-correcting codes
C. By diversity technique & Error-correcting codes
D. None of the mentioned

Answer: C

Slow fading can be minimized by using error-correcting codes and also by using the diversity technique to get additional uncorrelated estimates of a signal.

 

4. Fast fading can be minimized by

A. Robust modulation
B. Coding and interleaving
C. Robust modulation, Coding, and interleaving
D. None of the mentioned

Answer: C

Fast fading can be minimized by using coding and interleaving, using robust modulation, and introducing signal redundancy to increase the signaling rate.

 

5. The decision feedback equalizer has a linear traversal filter which is

A. Feed forward section
B. Feedback section
C. Feed forward section & Feedback section
D. None of the mentioned

Answer: A

The decision feedback filter has a feed-forward section which is a linear traversal filter.

 

6. The ISI and adjacent channel interference are removed by

A. Cancelling filter
B. Port processing equalizer
C. Cancelling filter & Port processing equalizer
D. None of the mentioned

Answer: C

The known ISI is introduced deliberately and the adjacent channel interference is removed by canceling the filter and post-processing equalizer.

 

7. The inter-leaver is more effective if the vehicle is

A. Fast
B. Slow
C. Fast & Slow
D. None of the mentioned

Answer: A

The inter-leaver is more effective in fast-running vehicles.

 

8. Channel noise is

A. Additive
B. White and stationary
C. Has infinite bandwidth
D. All of the mentioned

Answer: D

Channel noise is stationary, additive, and white with infinite bandwidth.

 

9. Which noise component plays a role in decision making?

A. Relevant noise
B. Non-relevant noise
C. Relevant & Non relevant noise
D. None of the mentioned

Answer: A

Only the relevant noise components play an important role in decision-making. It does not depend on non-relevant noise components.

 

10. Decision-making needs

A. Priors
B. Likelihoods
C. Priors & Likelihoods
D. None of the mentioned

Answer: C

Decision-making needs both priors and likelihoods and the Bayes decision rule combines them to achieve a minimum probability of error.

 

11. In matched filter _______ is performed.

A. Convolution
B. Correlation
C. Convolution & Correlation
D. None of the mentioned

Answer: C

In matched filter, a known signal is correlated with an unknown signal. It is similar to convolving an unknown signal with a time-reversed version of it.

 

12. Which needs more signal power?

A. BPSK
B. 16-QAM
C. BPSK & 16-QAM
D. None of the mentioned

Answer: B

16-QAM needs ten times more signal power than BPSK to attain the same probability of error.

 

13. Which has a higher transmission rate?

A. BPSK
B. 16-QAM
C. BPSK & 16-QAM
D. None of the mentioned

Answer: B

The rate of transmission of bits in 16-QAM is four times that of BPSK.

 

14. Symbol error probability can also be determined using the upper bound.

A. True
B. False

Answer: A
Certain signals lack symmetry in representation. For those signals, symbol error probability can be determined by using the upper bound.

 

15. Which signal sets are called equivalent signal sets?

A. Simplex
B. Bi-orthogonal
C. Simplex & Bi-orthogonal
D. None of the mentioned

Answer: C

Simplex signals and bi-orthogonal signals are examples of equivalent signal sets.

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16. For Neyman Pearson’s decision criterion, which is important?

A. Probability of false alarm
B. Probability of miss
C. Probability of false alarm & miss
D. None of the mentioned

Answer: C

For Neyman Pearson’s decision criterion two probabilities are important – the probability of false alarm and the probability of missing.

 

17. What are the parameters calculated for an estimator?

A. Error
B. Mean square error
C. Variance
D. All of the mentioned

Answer: D

Some of the parameters calculated for an estimator are error, mean square error, variance, sampling deviation, etc.

 

18. What is the source of performance degradation?

A. Thermal noise
B. Man-made noise
C. Natural noise
D. All of the mentioned

Answer: D

The sources of performance degradation are thermal noise, natural noise, and man-made noise.

 

19. The received power is attenuated by a factor called

A. Path loss
B. Free space loss
C. Path & Free space loss
D. None of the mentioned

Answer: C

The received power expressed in terms of the transmitted power is attenuated by a factor called path loss or free space loss.

 

20. Scintillation describes the fading caused by

A. Atmospheric changes
B. Physical changes
C. Thermal noise
D. Propagating effects

Answer: B

Scintillation is used to describe fading caused by physical changes in the propagating medium.

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