CWT Wireless Standards & Radio Frequency Fundamentals 2 — Questions and Answers
Question 1: Which IEEE 802.11 amendment introduced OFDMA as a key feature for improved multi-user efficiency?
- 802.11ac
- 802.11n
- 802.11ax (Correct answer)
- 802.11g
Correct answer: 802.11ax
802.11ax (Wi-Fi 6) introduced Orthogonal Frequency Division Multiple Access (OFDMA), allowing simultaneous transmission to multiple clients in the same channel.
Question 2: What is the primary frequency band used by Bluetooth Classic and Bluetooth Low Energy (BLE)?
- 5 GHz
- 2.4 GHz (Correct answer)
- 900 MHz
- 60 GHz
Correct answer: 2.4 GHz
Both Bluetooth Classic and BLE operate in the 2.4 GHz ISM band using frequency hopping spread spectrum.
Question 3: In RF propagation, what term describes signal power loss due to distance in free space?
- Reflection loss
- Free-space path loss (Correct answer)
- Diffraction loss
- Absorption loss
Correct answer: Free-space path loss
Free-space path loss (FSPL) is the reduction in signal power as it travels through free space, increasing with both frequency and distance.
Question 4: Which modulation scheme is used by 802.11ax to achieve its highest data rates?
- 64-QAM
- 256-QAM
- 1024-QAM (Correct answer)
- BPSK
Correct answer: 1024-QAM
802.11ax (Wi-Fi 6) uses 1024-QAM, encoding 10 bits per symbol to achieve higher throughput compared to the 256-QAM of Wi-Fi 5.
Question 5: What does the term 'channel bonding' refer to in wireless networking?
- Combining multiple APs into one logical unit
- Aggregating adjacent channels to increase bandwidth (Correct answer)
- Bonding wired and wireless links
- Linking channels for redundancy
Correct answer: Aggregating adjacent channels to increase bandwidth
Channel bonding combines two or more adjacent channels to create a wider channel (e.g., 40, 80, or 160 MHz) for higher throughput.
Question 6: What is the Effective Isotropic Radiated Power (EIRP)?
- The power input to the transmitter
- The total power radiated by a theoretical isotropic antenna in the direction of maximum gain (Correct answer)
- The noise floor of the receiver
- The antenna gain minus the cable loss
Correct answer: The total power radiated by a theoretical isotropic antenna in the direction of maximum gain
EIRP is the product of the transmitter's output power and the antenna gain (minus losses), representing the effective power radiated in the main beam.
Question 7: Which wireless standard operates exclusively in the 60 GHz band and is designed for very short-range, multi-gigabit links?
- 802.11ac
- 802.11ad (WiGig) (Correct answer)
- 802.11af
- 802.11ah
Correct answer: 802.11ad (WiGig)
IEEE 802.11ad, also known as WiGig, operates in the 60 GHz mmWave band and supports multi-gigabit speeds over very short distances (typically under 10 meters).
CWT Wireless Standards & Radio Frequency Fundamentals 2
Which IEEE 802.11 amendment introduced OFDMA as a key feature for improved multi-user efficiency?