CWS Research Methods & Evidence-Based Practice 2 — Questions and Answers
Question 1: During a post-deployment validation survey, a wireless engineer measures RSSI of -75 dBm at the cell edge. What is the MOST appropriate next step to confirm adequate coverage?
- Document and close the survey since -75 dBm meets minimum thresholds
- Cross-reference RSSI with SNR and throughput measurements at the same location (Correct answer)
- Increase AP transmit power across the entire network immediately
- Move the AP to a location closer to the measured cell edge
Correct answer: Cross-reference RSSI with SNR and throughput measurements at the same location
RSSI alone is insufficient; SNR and actual throughput measurements provide evidence of true link quality at the cell edge.
Question 2: Which type of wireless site survey is BEST suited for validating that a deployed network meets pre-defined KPIs before client acceptance?
- Predictive (RF modeling) survey
- Passive survey
- Active survey with associated client (Correct answer)
- Spectrum-only survey
Correct answer: Active survey with associated client
An active survey with an associated client measures real throughput and latency against the network, directly validating KPIs.
Question 3: A researcher wants to isolate the impact of co-channel interference on 2.4 GHz throughput in a dense office. What is the MOST rigorous method to control variables?
- Run iPerf tests during business hours on multiple days
- Disable all non-test APs on the same channel and measure baseline before re-enabling them (Correct answer)
- Use a predictive planning tool to estimate the interference
- Compare RSSI values from neighboring APs
Correct answer: Disable all non-test APs on the same channel and measure baseline before re-enabling them
Disabling non-test APs establishes a controlled baseline, allowing the researcher to attribute throughput changes specifically to co-channel interference.
Question 4: When documenting evidence for an 802.11r fast BSS transition implementation, which measurement BEST demonstrates successful roaming improvement?
- RSSI delta between old and new AP during roam
- Roam time in milliseconds captured via protocol analyzer before and after deployment (Correct answer)
- Number of probe requests observed during the roam event
- Signal-to-noise ratio at the roaming client
Correct answer: Roam time in milliseconds captured via protocol analyzer before and after deployment
Roam time in milliseconds, captured via protocol analysis, directly quantifies the improvement 802.11r provides over standard roaming.
Question 5: A spectrum analyzer shows a duty cycle of 85% on channel 6 from a non-Wi-Fi source. What is the MOST evidence-based action to take?
- Migrate all 2.4 GHz clients to 5 GHz and document the interferer type and duty cycle (Correct answer)
- Increase beacon interval to reduce management overhead on channel 6
- Switch channel 6 APs to channel 11 without further analysis
- Adjust the CCA threshold on channel 6 APs to -62 dBm
Correct answer: Migrate all 2.4 GHz clients to 5 GHz and document the interferer type and duty cycle
Documenting the interferer type and duty cycle creates an evidence trail, and migrating clients to 5 GHz removes them from the affected spectrum.
Question 6: Which statistical measure is MOST useful when comparing throughput samples collected across multiple APs to identify outliers in a wireless network audit?
- Mean (average) throughput per AP
- Standard deviation of throughput values across all APs (Correct answer)
- Maximum throughput recorded at any single AP
- Minimum RSSI value observed during the audit
Correct answer: Standard deviation of throughput values across all APs
Standard deviation reveals how widely throughput varies from the mean, making outlier APs statistically apparent.
Question 7: A CWS candidate is reviewing a competitor's site survey report that relies solely on predictive planning data with no on-site validation. What is the PRIMARY limitation of this approach?
- Predictive tools do not support 802.11ax (Wi-Fi 6) modulation schemes
- Physical environment factors such as furniture, people movement, and building materials are not fully captured in RF models (Correct answer)
- Predictive surveys cannot calculate EIRP values for regulatory compliance
- Predictive data is only valid for indoor environments below 10,000 sq ft
Correct answer: Physical environment factors such as furniture, people movement, and building materials are not fully captured in RF models
RF propagation models approximate real-world conditions but cannot fully account for dynamic physical variables, making on-site validation essential.
CWS Research Methods & Evidence-Based Practice 2
During a post-deployment validation survey, a wireless engineer measures RSSI of -75 dBm at the cell edge.
What is the MOST appropriate next step to confirm adequate coverage?