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14 Cards in this Set

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Define asymmetric power issues:

Two communicating devices have differing transmit power levels that mightprevent them from reaching each other.

To support certain data rates, what must be true for those specific data rates?

-Signal must be greater than receiver sensitivity


-Signal to noise ratio must be high enough to support the modulation and coding schemes required for that rate

What do spatial streams require?

-Multipath conditions


-Higher SNR

As the client moves away from the AP and the currentMCS becomes less reliable, what is the process used to select the next MCS?

Dynamic Rate Shifting

How would you reduce the usable cell size of an AP without lowering the power?

Disabling the lower throughput rates

Define Guard Interval

Guard Interval is intended to avoid signal loss from multipath effect. In wireless transmission, RF signals reach the receiving antenna by two or more paths, if the latter information symbol reaches the antenna too fast, signal may interfere with the earlier symbol.

When should a short guard interval be used?

1. When intending to improve the throughput, enable short GI can improve the throughput about 10%.


2. If the multipath effect is not too serious (not too many metals or other reflecting materials), you can enable short GI.


3. If you are using 802.11n or 802.11ac only, you can enable short GI. In another word, when using mixed mode, please disable the short GI, which may cause issues.

Define MCS and their rates

MCS 9 - 600 Mbps


MCS 8 - 540 Mbps


MCS 7 -450 Mbps


MCS 6 -405 Mbps


MCS 5 -360 Mbps


MCS 4 -270 Mbps


MCS 3 -180 Mbps


MCS 2 -135 Mbps


MCS 1 -90 Mbps


MCS 045 Mbps

To providerobust wireless coverage to an ever-increasing area, you should use the following twoprongedapproach:

-Tune the cell size based on data rates and performance.


-Add additional APs to build an ESS that covers more area.

The decision to roam is made by:

The wireless client driver (Roaming algorithms are vendor specific)

The 802.11k-2008 amendment, now incorporated into the 802.11-2012 standard,defines a more efficient roaming scheme:

The client will request a list of other nearby APs. This is known as AP assisted roaming.

What is the Cisco recommended cell overlap?

10–15 percent overlap for most data applications and 15–20 percent overlap for voice. This gives a client device some continued coverage even after the RSSI of its associatedAP falls below a threshold and a roam might be triggered.

Define "Channel Reuse"

Alternating channels to avoid overlap of the same channel

Describe how Real Time Location Services (RTLS) work:

A device is located by triangulating the RSSI from several APs that can receive its signal.