CWT Wireless Standards & Radio Frequency Fundamentals 3

Question 1

What is the maximum number of spatial streams supported by 802.11ac Wave 2?

Accepted Answer

8

Answer

802.11ac Wave 2 supports up to 8 spatial streams using MU-MIMO, allowing simultaneous transmission to multiple clients.

Question 2

In the 5 GHz band, what does the acronym DFS stand for?

Accepted Answer

Dynamic Frequency Selection

Answer

Dynamic Frequency Selection (DFS) is a mechanism that requires Wi-Fi devices to detect radar signals and switch channels to avoid interference with radar systems.

Question 3

Which RF phenomenon occurs when a signal travels two different paths and the delayed copy destructively interferes with the primary signal?

Accepted Answer

Multipath fading

Answer

Multipath fading occurs when reflected or scattered copies of a signal arrive at the receiver out of phase, causing destructive interference and signal degradation.

Question 4

What is the guard interval in OFDM, and why is it used?

Accepted Answer

A time gap between symbols to prevent intersymbol interference from multipath

Answer

The guard interval is a brief silent period inserted between OFDM symbols to allow multipath echoes to die out before the next symbol is received, preventing ISI.

Question 5

Which regulatory body allocates RF spectrum and sets EIRP limits for unlicensed devices in the United States?

Accepted Answer

FCC

Answer

The Federal Communications Commission (FCC) regulates RF spectrum allocation and establishes maximum EIRP limits for unlicensed devices in the US under Part 15 rules.

(CWT) Certified Wireless Technician Practice Test

(CWT) Certified Wireless Technician Practice Test

CWT Wireless Standards & Radio Frequency Fundamentals 3