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26.
What is the maximum number of spatial streams supported by 802.11ac?
- A.1
- B.2
- C.4
- D.8
- E.16
- Answer & Explanation
- Report
Answer : [D]
Explanation :
Explanation :
| 802.11ac supports a maximum of eight spatial streams, although only three are supported in Wave 1 and four in Wave 2. |
27.
Which one of the following organizations certifies 802.11 interoperability?
- A.ITU-R
- B.FCC
- C.IEEE
- D.Wi-Fi Alliance
- E.Cisco
- Answer & Explanation
- Report
Answer : [D]
Explanation :
Explanation :
| Only the Wi-Fi Alliance tests and certifies wireless products according to industry standards. |
28.
An 802.11 transmitter is configured to send a signal on channel 11. Someone reports
a problem receiving the signal, so you investigate and find a second transmitter broadcasting on channel 11. Which one of the following best describes the problem?
- A.Path interference
- B.Adjacent channel interference
- C.Co-channel interference
- D.Cross-channel interference
- Answer & Explanation
- Report
Answer : [C]
Explanation :
Explanation :
| Because both transmitters are using the same channel, the interference is described as co-channel. |
29.
Suppose that you place a new 802.11n transmitter in a building, but notice that there
are other signals already coming from transmitters in the same general area. To avoid
interference problems, how much greater should your transmitter’s signal be above all
of the others to provide the best signal?
- A.0 dB
- B.+3 dB
- C.+5 dB
- D.+10 dB
- E.+20 dB
- Answer & Explanation
- Report
Answer : [E]
Explanation :
Explanation :
| Cisco recommends a separation of at least 19 dB, so +20 dB is the only correct answer. |
30.
The transmitter in your office sends its signal on 2.4-GHz channel 1. Suppose
that someone in a neighboring office sets up a new wireless Wirelessr. He notices your
signal on channel 1, so he chooses channel 2 instead. Which one of the following
might adversely affect the wireless operation?
- A.Co-channel interference
- B.Neighboring channel interference
- C.Wideband interference
- D.Excessive SNR
- Answer & Explanation
- Report
Answer : [B]
Explanation :
Explanation :
| The two channels being used are adjacent, so their signals overlap by some degree. The resulting interference is called adjacent channel interference. |
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