CWS CWS Site Survey Fundamentals 4 — Questions and Answers
Question 1: During a site survey, which measurement is used to evaluate the RF channel's ability to support high data rates under real traffic conditions?
- Received Signal Strength Indicator (RSSI) alone
- Retry rate and frame error rate under load (Correct answer)
- The AP's advertised maximum theoretical throughput
- The number of SSIDs broadcast by the AP
Correct answer: Retry rate and frame error rate under load
Retry rate and frame error rate under actual traffic load reveal real-world channel quality that static RSSI measurements cannot capture.
Question 2: A CWS is asked to design a high-density venue (e.g., a stadium). Which AP placement strategy is MOST appropriate?
- Mount APs on the ceiling as high as possible with maximum transmit power
- Use many low-power APs with directional antennas aimed at seating sections (Correct answer)
- Deploy a single high-power AP per section to maximize coverage radius
- Avoid 5 GHz because it doesn't penetrate crowds as well as 2.4 GHz
Correct answer: Use many low-power APs with directional antennas aimed at seating sections
High-density environments require many cell-splitting APs with reduced power and directional antennas to serve large numbers of clients in small, defined areas.
Question 3: What is the purpose of a 'coverage overlap' requirement of 15–20% between adjacent APs in an enterprise Wi-Fi design?
- To allow clients to roam without losing connectivity between cells (Correct answer)
- To maximize interference between APs to improve throughput
- To ensure both APs use the same channel for coordination
- To comply with FCC Part 15 co-location rules
Correct answer: To allow clients to roam without losing connectivity between cells
A 15–20% overlap zone ensures a client always has a strong signal from at least two APs, enabling seamless roaming handoffs without coverage gaps.
Question 4: Which factor has the GREATEST impact on 5 GHz signal attenuation compared to 2.4 GHz in office environments?
- 5 GHz signals are more susceptible to rain fade outdoors
- Higher frequency signals experience greater material penetration loss through walls (Correct answer)
- 5 GHz APs consume more power and overheat faster
- 5 GHz channels are narrower, reducing effective throughput
Correct answer: Higher frequency signals experience greater material penetration loss through walls
Higher frequencies lose more energy when passing through building materials, meaning 5 GHz signals attenuate more rapidly than 2.4 GHz through walls and floors.
Question 5: When documenting a site survey, which data should ALWAYS be included in the final deliverable?
- Only the heatmap images; no raw data is needed
- Floor plans with AP placement, channel assignments, RSSI heatmaps, and identified interference sources (Correct answer)
- The AP vendor's marketing specifications and MSRP pricing
- The surveyor's personal travel expenses and billable hours
Correct answer: Floor plans with AP placement, channel assignments, RSSI heatmaps, and identified interference sources
A complete site survey report includes annotated floor plans, AP locations, channel plans, RSSI/SNR heatmaps, and documentation of any interference sources found.
Question 6: A surveyor is testing an outdoor point-to-point Wi-Fi link. Which concept describes the elliptical zone around the direct line of sight that must be kept 60% clear of obstructions?
- Dead zone
- Fresnel zone (Correct answer)
- RF shadow zone
- Multipath reflection corridor
Correct answer: Fresnel zone
The Fresnel zone is an elliptical region around the line-of-sight path; obstructions within the first Fresnel zone (especially the inner 60%) significantly degrade link performance.
Question 7: What does 'channel reuse' mean in the context of a Wi-Fi site survey design?
- Using the same frequency channel on geographically separated APs that won't interfere with each other (Correct answer)
- Assigning every AP in a building to the same channel to simplify management
- Recycling old APs from a previous installation to reduce costs
- Reusing 2.4 GHz channels in the 5 GHz band for backward compatibility
Correct answer: Using the same frequency channel on geographically separated APs that won't interfere with each other
Channel reuse assigns the same channel to APs that are far enough apart that their signals don't overlap, maximizing spectrum efficiency across a large deployment.
CWS CWS Site Survey Fundamentals 4
During a site survey, which measurement is used to evaluate the RF channel's ability to support high data rates under real traffic conditions?