CWDP Capacity Planning and High-Density Design — Questions and Answers
Question 1: What is the recommended approach for AP placement in a high-density wireless environment?
- Deploy APs at lower power with more density and use smaller cells with directional antennas (Correct answer)
- Use fewer APs at maximum power for broader coverage
- Place APs only along exterior walls
- Deploy one AP per floor with omnidirectional antennas
Correct answer: Deploy APs at lower power with more density and use smaller cells with directional antennas
High-density environments require more APs at lower power levels to create smaller cells, reducing co-channel interference and providing dedicated capacity per area, often using directional antennas to control coverage.
Question 2: How should channel planning be approached in a multi-floor building to minimize co-channel interference?
- Use a 3D channel reuse pattern ensuring the same channel is not used on adjacent APs vertically or horizontally (Correct answer)
- Use the same channel on every floor for consistency
- Only use channel 1 throughout the building
- Assign channels randomly to each AP
Correct answer: Use a 3D channel reuse pattern ensuring the same channel is not used on adjacent APs vertically or horizontally
A 3D channel reuse plan considers both horizontal and vertical AP adjacencies, ensuring that co-channel APs are separated by enough distance and floor attenuation to prevent significant co-channel interference.
Question 3: What is airtime fairness and why is it important in WLAN design?
- A mechanism ensuring slow clients don't monopolize the wireless medium, degrading performance for faster clients (Correct answer)
- Equal bandwidth allocation to all connected devices
- A regulatory requirement for public Wi-Fi networks
- A feature that limits each client to equal time online
Correct answer: A mechanism ensuring slow clients don't monopolize the wireless medium, degrading performance for faster clients
Airtime fairness allocates equal time on the wireless medium to each client regardless of their data rate, preventing slow clients from consuming disproportionate airtime and degrading the experience for faster clients.
Question 4: What factors determine the number of APs needed for a high-density deployment?
- Number of concurrent clients, application bandwidth requirements, and acceptable contention ratio (Correct answer)
- Only the square footage of the area
- The number of SSID names configured
- The brand of access points being used
Correct answer: Number of concurrent clients, application bandwidth requirements, and acceptable contention ratio
Capacity planning considers the expected number of concurrent devices, bandwidth requirements per application, acceptable contention ratios, device capabilities, and traffic patterns to determine AP count.
Question 5: What is band steering and how does it benefit wireless network performance?
- Encouraging dual-band clients to connect to the 5 GHz band for better performance and reduced 2.4 GHz congestion (Correct answer)
- Physically pointing antennas in specific directions
- Forcing all clients to use 2.4 GHz for better range
- Automatically selecting the best channel within a band
Correct answer: Encouraging dual-band clients to connect to the 5 GHz band for better performance and reduced 2.4 GHz congestion
Band steering detects dual-band capable clients and encourages them to connect to the 5 GHz band, which typically offers more available channels, wider channel widths, and less congestion than the crowded 2.4 GHz band.
Question 6: What is the impact of hidden node problem on WLAN capacity?
- Clients that cannot detect each other transmit simultaneously, causing collisions at the AP (Correct answer)
- Hidden network names reduce available bandwidth
- Clients behind walls cannot connect to the network
- Access points hidden in ceiling tiles have reduced range
Correct answer: Clients that cannot detect each other transmit simultaneously, causing collisions at the AP
The hidden node problem occurs when two clients can communicate with the same AP but cannot detect each other, leading to simultaneous transmissions that collide at the AP, wasting airtime and reducing throughput.
CWDP Capacity Planning and High-Density Design
What is the recommended approach for AP placement in a high-density wireless environment?