Virtual Labs

Flat Fading

1. What is the key characteristic of 'flat fading'?

a: It affects only the high-frequency parts of a signal. Explanation

Explanation

b: It affects only the low-frequency parts of a signal. Explanation

Explanation

c: It affects all frequency components of the signal in a similar way. Explanation

Explanation

d: It is a signal gain, not a loss. Explanation

Explanation

2. What does 'outage probability' define?

a: The probability that the system is powered down for maintenance. Explanation

Explanation

b: The probability that the received signal quality falls below a usable threshold. Explanation

Explanation

c: The likelihood that a user moves out of the cell's coverage area. Explanation

Explanation

d: The probability that a new call is successfully connected. Explanation

Explanation

3. What does the 'Level Crossing Rate' (LCR) measure?

a: How often the signal strength crosses a specific level. Explanation

Explanation

b: The average speed of the mobile user. Explanation

Explanation

c: The total number of users in a cell. Explanation

Explanation

d: The average time a signal stays in a faded state. Explanation

Explanation

4. What is the 'Average Fade Duration' (ADF)?

a: The average time it takes to connect a call. Explanation

Explanation

b: The average time the signal stays below a specific level once it drops. Explanation

Explanation

c: The frequency at which the signal fades the most. Explanation

Explanation

d: The total duration of the entire communication. Explanation

Explanation

5. What does the diversity technique 'Selection Combining' (SC) do?

a: It combines all received signals by adding them together. Explanation

Explanation

b: It averages the quality of all received signals. Explanation

Explanation

c: It discards all signals and waits for a better one. Explanation

Explanation

d: It selects the single best signal from multiple received paths. Explanation

Explanation

6. How does 'Maximal-Ratio Combining' (MRC) improve the signal?

a: It selects only the signal with the lowest noise. Explanation

Explanation

b: It inverts the phase of bad signals to cancel them out. Explanation

Explanation

c: It intelligently combines all signals, giving more weight to the stronger ones. Explanation

Explanation

d: It only uses the two strongest signals and discards the rest. Explanation

Explanation

7. How does the performance of MRC generally compare to Selection Combining (SC) in a SISO system?

a: MRC provides a better improvement in signal quality. Explanation

Explanation

b: SC provides a better improvement in signal quality. Explanation

Explanation

c: They both provide the exact same level of improvement. Explanation

Explanation

d: SC is better for LCR, but MRC is better for ADF. Explanation

Explanation

8. What is the primary goal of using diversity combining (SC or MRC) in a fading environment?

a: To increase the Level Crossing Rate. Explanation

Explanation

b: To increase the Average Fade Duration. Explanation

Explanation

c: To decrease the outage probability. Explanation

Explanation

d: To make the fading 'flat'. Explanation

Explanation

9. A system is described as 'SISO'. What does this mean?

a: It has multiple transmit and multiple receive antennas. Explanation

Explanation

b: It has multiple transmit and a single receive antenna. Explanation

Explanation

c: It has a single transmit and a single receive antenna. Explanation

Explanation

d: It has a single transmit and multiple receive antennas. Explanation

Explanation

10. If a diversity scheme is working well, what change would you expect in the LCR and ADF?

a: Both LCR and ADF would increase. Explanation

Explanation

b: LCR would increase, but ADF would decrease. Explanation

Explanation

c: Both LCR and ADF would decrease. Explanation

Explanation

d: LCR would decrease, but ADF would increase. Explanation

Explanation