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Difficulty: HardWireless Networking Standards and Technologies

A network administrator is troubleshooting severe packet loss and latency spikes on a 2.4 GHz wireless network in a commercial office building. A spectrum analyzer reveals heavy traffic from surrounding tenant access points operating on channels 1 and 11. To avoid sharing a channel with those networks, a junior technician previously set the office access point to channel 4 with a 40 MHz channel width. Which of the following configuration changes should the administrator implement to eliminate adjacent channel overlap and align with 2.4 GHz wireless deployment best practices?

  1. Reconfigure the access point to operate on channel 6 using a 20 MHz channel width.Answer
  2. B
    Reconfigure the access point to operate on channel 3 using a 20 MHz channel width.
  3. C
    Increase the channel width to 80 MHz on channel 4 to override neighboring signals.
  4. D
    Set the access point to channel 1 while retaining the 40 MHz channel width.

Answer

Reconfigure the access point to operate on channel 6 using a 20 MHz channel width.
In North American and standard 2.4 GHz Wi-Fi implementations, the non-overlapping channels for 20 MHz widths are channels 1, 6, and 11. With nearby networks using channels 1 and 11, moving the access point to channel 6 with a 20 MHz channel width places the transmission into the single remaining non-overlapping slot, eliminating adjacent channel interference.

Step-by-Step Solution

1
Analyze the 2.4 GHz frequency band spectrum and channel separation rules.
Determine that 2.4 GHz channels are spaced 5 MHz apart, while standard Wi-Fi transmissions require 20 MHz of bandwidth. This leaves only three non-overlapping 20 MHz channels: 1, 6, and 11.
Using any intermediate channel (such as 2, 3, 4, or 5) causes adjacent channel interference (ACI), which prevents CSMA/CA from functioning efficiently.
2
Evaluate the current access point configuration (channel 4, 40 MHz width).
Identify that channel 4 overlaps directly with both channel 1 and channel 6 signals, and a 40 MHz width expands the transmission footprint across seven channels.
40 MHz channel bonding in the 2.4 GHz band spans almost the entire usable spectrum, making non-overlapping operation impossible.
3
Select the correct channel and width parameters given external network usage on channels 1 and 11.
Reconfigure the access point to channel 6 at 20 MHz.
Channel 6 is the only standard non-overlapping 20 MHz channel remaining unoccupied by adjacent tenant networks.

Key Concept

2.4 GHz Non-Overlapping Channels and Channel Width Planning
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Topics

Wireless Networking Standards and Technologies

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