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Difficulty: MediumWireless Networking Standards and Technologies

A field technician is deploying three 802.11n wireless access points along a single corridor to provide continuous coverage for mobile devices operating on the 2.4 GHz band. To minimize signal interference and packet retransmissions between adjacent access points, which set of channel assignments should the technician use?

  1. Channels 1, 6, and 11Answer
  2. B
    Channels 1, 2, and 3
  3. C
    Channels 2, 6, and 10
  4. D
    Channels 1, 5, and 9

Answer

Assigning channels 1, 6, and 11 ensures that the three access points operate on non-overlapping frequencies in the 2.4 GHz band.
The correct selection uses channels 1, 6, and 11. In the 2.4 GHz wireless spectrum (channels 1–11), each standard channel occupies a 20 MHz bandwidth with center frequencies spaced 5 MHz apart. Consequently, channels 1, 6, and 11 are the only three 20 MHz channels in North America that do not overlap with one another, preventing adjacent-channel interference.

Step-by-Step Solution

1
Identify the operating frequency band and channel bandwidth specifications.
The 2.4 GHz Wi-Fi spectrum uses 20 MHz wide channels spaced 5 MHz apart across channels 1 through 11.
Understanding the channel spacing requirement is necessary to determine which channel numbers do not overlap.
2
Calculate the minimum separation needed between channel center frequencies.
A minimum spacing of 5 channels (25 MHz center-to-center offset) is required to prevent frequency overlap.
This spacing guarantees that the sidebands of adjacent Wi-Fi signals do not interfere with each other.
3
Select the standard set of 3 non-overlapping channels.
Channels 1, 6, and 11 provide complete isolation across three adjacent coverage cells.
This configuration avoids both co-channel and adjacent-channel interference in a multi-AP deployment.

Key Concept

2.4 GHz Non-Overlapping Wi-Fi Channels
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Topics

Wireless Networking Standards and Technologies

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