CWS CWS 802.11 Standards and Protocols 4 — Questions and Answers
Question 1: Which 802.11 amendment introduced the 6 GHz band for Wi-Fi operation?
- 802.11ax
- 802.11be
- 802.11ax with 6 GHz (Wi-Fi 6E) (Correct answer)
- 802.11ad
Correct answer: 802.11ax with 6 GHz (Wi-Fi 6E)
Wi-Fi 6E is the industry name for 802.11ax devices that also operate in the newly opened 6 GHz band, providing additional spectrum and reducing congestion.
Question 2: What is the maximum number of spatial streams supported by 802.11ac?
- 2
- 4
- 8 (Correct answer)
- 16
Correct answer: 8
802.11ac supports up to 8 spatial streams with MU-MIMO, though real-world deployments typically use 3–4 streams.
Question 3: In the context of 802.11 DCF, what does the acronym DIFS stand for?
- Distributed Inter-Frame Space (Correct answer)
- Dynamic Interface Fragmentation Standard
- Downlink Interference Free Slot
- Dual Interface Frame Sequence
Correct answer: Distributed Inter-Frame Space
DIFS (Distributed Inter-Frame Space) is the minimum idle time a station must wait before attempting a transmission using the DCF contention method.
Question 4: Which statement correctly describes 802.11 frame aggregation?
- It combines multiple IP packets into a single TCP segment
- A-MSDU and A-MPDU bundle multiple frames to reduce per-frame overhead (Correct answer)
- Aggregation is only supported in the 5 GHz band
- Frame aggregation was introduced in 802.11ac, not 802.11n
Correct answer: A-MSDU and A-MPDU bundle multiple frames to reduce per-frame overhead
A-MSDU (Aggregate MAC Service Data Unit) and A-MPDU (Aggregate MAC Protocol Data Unit) were introduced in 802.11n to bundle frames, reducing header and acknowledgment overhead.
Question 5: What is the purpose of the 802.11k Radio Resource Management (RRM) amendment?
- Mandate minimum EIRP levels for outdoor deployments
- Enable STAs to report channel and neighbor AP measurements to aid roaming decisions (Correct answer)
- Manage power allocation across multiple radios on an AP
- Define spectrum mask requirements for each PHY type
Correct answer: Enable STAs to report channel and neighbor AP measurements to aid roaming decisions
802.11k allows APs to collect radio measurement reports from clients, providing neighbor lists and signal data that help clients make smarter, faster roaming decisions.
Question 6: What frequency band does 802.11ad (WiGig) operate in?
- 2.4 GHz
- 5 GHz
- 6 GHz
- 60 GHz (Correct answer)
Correct answer: 60 GHz
802.11ad operates in the 60 GHz mmWave band, offering multi-gigabit speeds over very short distances with minimal wall penetration.
Question 7: During an active scan, a 802.11 client transmits which frame type to discover nearby APs?
- Association Request
- Probe Request (Correct answer)
- Authentication Request
- Beacon
Correct answer: Probe Request
During active scanning, the client sends Probe Request frames; nearby APs respond with Probe Response frames containing BSS capability information.
CWS CWS 802.11 Standards and Protocols 4
Which 802.11 amendment introduced the 6 GHz band for Wi-Fi operation?