Wireless Standards & Radio Frequency Fundamentals Flashcards

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

Answer: 8

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

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

Answer: Dynamic Frequency Selection

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.

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

Answer: Multipath fading

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

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

Answer: A time gap between symbols to prevent intersymbol interference from multipath

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.

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

Answer: FCC

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

What Wi-Fi generation corresponds to the IEEE 802.11ac standard?

Answer: Wi-Fi 5

The Wi-Fi Alliance designated 802.11ac as Wi-Fi 5, which operates in the 5 GHz band and supports MU-MIMO and up to 160 MHz channels.

What is the purpose of Transmit Power Control (TPC) in wireless networks?

Answer: To dynamically reduce transmit power to minimize interference with adjacent systems

TPC allows devices to reduce their transmit power when maximum power is not needed, reducing co-channel interference and meeting regulatory requirements on DFS channels.