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31.
Which one of the following is the best strategy for avoiding interference between
neighboring channels in the 2.4-GHz band?
- A.Use any channel number that seems to be available
- B.Leverage 802.11n for 40-MHz aggregated channels
- C.Use only channels that are spaced four numbers apart, beginning with channel 1
- D.Use only channels that are spaced five numbers apart, beginning with channel 1
- Answer & Explanation
- Report
Answer : [D]
Explanation :
Explanation :
| In the 2.4-GHz band, channels 1, 6, and 11 are the only ones that are spaced far enough apart (five channel numbers) that they do not overlap. |
32.
Which one of the following is the primary cause of free space path loss?
- A.Spreading
- B.Absorption
- C.Humidity levels
- D.Magnetic field decay
- Answer & Explanation
- Report
Answer : [A]
Explanation :
Explanation :
| Energy traveling in an electromagnetic wave spreads in three dimensions, weakening the signal strength over a distance. |
33.
Which one of the following has the shortest effective range in free space, assuming
that the same transmit power level is used for each?
- A.An 802.11g device
- B.An 802.11a device
- C.An 802.11b device
- D.None of these answers
- Answer & Explanation
- Report
Answer : [B]
Explanation :
Explanation :
| The 802.11b and g devices operate at 2.4 GHz, which is less affected by free space loss than the 802.11a device, at 5 GHz. |
34.
Suppose that an 802.11a device moves away from a transmitter. As the signal strength
decreases, which one of the following might the device or the transmitter do to
improve the signal quality along the way?
- A.Aggregate more channels
- B.Use more radio chains
- C.Switch to a more complex modulation scheme
- D.Switch to a less-complex modulation scheme
- Answer & Explanation
- Report
Answer : [D]
Explanation :
Explanation :
| By switching to a less-complex modulation scheme, more of the data stream can be repeated to overcome worsening RF conditions. This can be done automatically through DRS. |
35.
When RF signals are reflected by objects in a building, which one of the following
best describes the result that might be experienced at a receiver?
- A.Fresnel loss
- B.Multipath
- C.Cross-channel fading
- D.Free space path loss
- Answer & Explanation
- Report
Answer : [B]
Explanation :
Explanation :
| As a signal is reflected, a new copy travels in a different direction. Each copy of the signal takes a different path to reach the receiver; thus, the name multipath. |
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