Question

Difficulty: MediumTroubleshooting Wireless Connectivity and Signal Issues

An IT technician is troubleshooting severe throughput degradation and excessive frame retransmissions on a newly configured 2.4 GHz wireless network in an office suite. A site survey reveals that three nearby access points serving the area are operating on channels 1, 3, and 5. Which of the following modifications should the technician make to resolve the interference?

  1. Reconfigure the access points to operate on channels 1, 6, and 11.Answer
  2. B
    Set all three access points to operate on channel 6 to unify the wireless channel assignment.
  3. C
    Increase the radio transmit power on all access points to overpower the adjacent signal noise.
  4. D
    Configure an IP helper address on the wireless controller to ensure clients receive valid DHCP leases.

Answer

Reconfigure the access points to operate on channels 1, 6, and 11.
The 2.4 GHz Wi-Fi spectrum uses 20 MHz channel widths spaced 5 MHz apart. To avoid adjacent-channel interference (ACI), access points must be configured on non-overlapping channels (1, 6, and 11). Operating APs on channels 1, 3, and 5 results in overlapping frequency ranges that cause heavy packet corruption and retransmissions.

Step-by-Step Solution

1
Analyze the reported symptoms and current channel assignment
Identified that channels 1, 3, and 5 overlap with one another in the 2.4 GHz band, leading to adjacent-channel interference (ACI).
Channels 1, 3, and 5 share frequency ranges, causing RF energy from one channel to corrupt signals on adjacent channels.
2
Determine the standard non-overlapping channel scheme for 2.4 GHz Wi-Fi
Channels 1, 6, and 11 provide 20 MHz spacing with no frequency overlap.
20 MHz wide channels require 25 MHz of separation between center frequencies to prevent overlapping boundaries.
3
Select the appropriate remedial action
Reassigning the access points to channels 1, 6, and 11 resolves ACI.
Proper channel separation eliminates adjacent channel interference and restores normal wireless throughput.

Key Concept

2.4 GHz Non-Overlapping Channel Selection
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