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Difficulty: Very hardWireless Network Deployment and Standards

A network engineering team is designing a multi-floor high-density enterprise wireless deployment using IEEE 802.11ax access points operating in both the 2.4 GHz and 5 GHz bands. During the predictive site survey phase, the team must configure the deployment to minimize co-channel interference (CCI), prevent coverage overlap issues, and optimize client band steering toward 5 GHz. Which of the following technical design decisions and configuration strategies should the team implement? (Select THREE).

  1. Stagger 2.4 GHz channel assignments using non-overlapping channels 1, 6, and 11 across adjacent access points, while selectively disabling 2.4 GHz radios on redundant access points in dense areas.Answer
  2. Restrict 5 GHz channel widths to 20 MHz or 40 MHz rather than 80 MHz or 160 MHz channel bonding in high-density areas.Answer
  3. Lower the transmit power on 2.4 GHz radios relative to 5 GHz radios to equalize coverage cell sizes and encourage 5 GHz client association.Answer
  4. D
    Assign channels 1, 3, 6, and 9 sequentially across adjacent 2.4 GHz access points to distribute client connections across additional channel frequencies.
  5. E
    Configure 80 MHz channel bonding across both 2.4 GHz and 5 GHz bands to maximize per-client theoretical throughput across all deployed radios.
  6. F
    Set 2.4 GHz radios to maximum transmit power across all access points to maintain client connectivity during roaming between floors.

Answer

The correct strategies are: 1) Staggering 2.4 GHz channels using non-overlapping channels 1, 6, and 11 while selectively disabling redundant 2.4 GHz radios; 2) Restricting 5 GHz channel widths to 20 MHz or 40 MHz to preserve available non-overlapping channels; and 3) Lowering 2.4 GHz transmit power relative to 5 GHz to balance cell sizes and foster band steering.
In high-density enterprise wireless deployments, effective RF planning relies on eliminating channel overlap, maximizing independent channel count, and balancing cell boundaries. First, using non-overlapping 2.4 GHz channels (1, 6, and 11) and turning off excess 2.4 GHz radios prevents excessive co-channel overlap. Second, keeping 5 GHz channel widths to 20 MHz or 40 MHz preserves non-overlapping channel availability, avoiding co-channel interference caused by wide 80 MHz channel bonding. Third, turning down 2.4 GHz transmit power reduces its coverage radius to match 5 GHz, guiding dual-band clients onto the faster 5 GHz band.

Step-by-Step Solution

1
Analyze 2.4 GHz spectrum planning and channel allocation constraints.
Identify that 2.4 GHz only offers three non-overlapping 20 MHz channels (1, 6, and 11 in standard domain planning). Adjacent or bonded channel assignments (such as channels 3 or 9, or 80 MHz bonding) induce severe interference. Disabling redundant 2.4 GHz radios reduces co-channel interference in dense deployments.
2.4 GHz signals travel farther and penetrate obstacles better, causing excessive cell overlap if every AP broadcasts 2.4 GHz at high power.
2
Evaluate 5 GHz channel width design in high-density deployments.
Determine that while 80 MHz channel bonding increases throughput, it reduces the total count of non-overlapping channels. High-density AP environments require more non-overlapping channels (using 20 MHz or 40 MHz channel widths) to prevent co-channel interference.
Maximizing channel count per spatial area takes priority over individual peak channel bandwidth in dense enterprise environments.
3
Assess transmit power matching and cell boundary management across bands.
Reduce 2.4 GHz transmit power so its RF footprint matches the smaller footprint of the 5 GHz radio on the same access point.
Equalizing coverage cell boundaries ensures smooth client roaming and encourages dual-band client devices to connect to the less congested 5 GHz band.

Key Concept

Enterprise Wireless Cell Planning, Channel Allocation, and Co-Channel Interference Mitigation
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Topics

Wireless Network Deployment and Standards

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