CWDP Channel Planning and RF Design 1 — Questions and Answers
Question 1: What is the primary goal of channel planning in a WLAN deployment?
- Maximize the number of access points deployed
- Minimize co-channel interference between access points (Correct answer)
- Increase transmit power across all access points
- Reduce the total number of SSIDs broadcasted
Correct answer: Minimize co-channel interference between access points
Channel planning aims to minimize co-channel interference by ensuring APs using the same channel are spaced far enough apart that their signals do not significantly overlap.
Question 2: In the 2.4 GHz band, how many non-overlapping 20 MHz channels are available in the United States?
- 11
- 14
- 3 (Correct answer)
- 6
Correct answer: 3
Only channels 1, 6, and 11 are non-overlapping in the 2.4 GHz band in the US, giving exactly 3 usable non-overlapping channels.
Question 3: What is co-channel interference (CCI) in a WLAN environment?
- Interference caused by devices operating on adjacent channels
- Interference between access points operating on the same channel (Correct answer)
- Interference originating from non-802.11 RF emitters
- Interference caused by multipath signal reflections
Correct answer: Interference between access points operating on the same channel
CCI occurs when two or more APs share the same channel and their coverage areas overlap, causing them to contend for airtime and degrade performance.
Question 4: Which channel planning strategy assigns the same channel to APs that are sufficiently separated to prevent interference?
- Adjacent channel planning
- Random channel assignment
- Frequency reuse planning (Correct answer)
- Dynamic Frequency Selection
Correct answer: Frequency reuse planning
Frequency reuse planning deliberately reuses the same channels at APs spaced far enough apart so their coverage cells do not interfere with each other.
Question 5: In the 5 GHz band using 20 MHz channels, approximately how many non-overlapping channels are available in the US across UNII-1, UNII-2, UNII-2e, and UNII-3?
- 3
- 11
- 25 (Correct answer)
- 45
Correct answer: 25
The US 5 GHz band provides approximately 25 non-overlapping 20 MHz channels when all available UNII sub-bands are considered, making it far richer than 2.4 GHz.
Question 6: What is Adjacent Channel Interference (ACI) in wireless networking?
- Interference between APs using identical channels
- Interference between APs on channels that partially overlap in frequency (Correct answer)
- Interference from external RF sources outside the building
- Interference caused by the same SSID broadcasted on multiple APs
Correct answer: Interference between APs on channels that partially overlap in frequency
ACI occurs when APs use channels that are close but not identical in frequency, causing partial spectral overlap that degrades signal quality.
Question 7: Which tool is most commonly used to visualize RF channel assignments and coverage across a floor plan during the design phase?
- Protocol analyzer
- Spectrum analyzer
- RF planning / heat map software (Correct answer)
- Network management system
Correct answer: RF planning / heat map software
RF planning software (such as Ekahau or iBwave) generates predictive heat maps that overlay channel assignments and coverage patterns onto floor plans before deployment.
CWDP Channel Planning and RF Design 1
What is the primary goal of channel planning in a WLAN deployment?