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Zorluk: Çok zorWireless Network Deployment and Standards

A network architect is performing a spectral audit of a high-density warehouse deployment operating in the 2.4 GHz ISM band. The physical installation consists of five adjacent access points (APs) mounted on a single high-ceiling beam line. The current channel configuration assigns the APs to channels 1, 3, 6, 8, and 11 with equal transmit power. Which statement accurately identifies the primary issue with this channel plan and its operational impact on the wireless network?

  1. Channels 3 and 8 overlap with adjacent channels 1, 6, and 11, causing severe adjacent-channel interference (ACI) and frame corruption because overlapping signals cannot be decoded or coordinated by CSMA/CA.Cevap
  2. B
    Channels 1, 3, 6, 8, and 11 are all standard non-overlapping 2.4 GHz channels, but assigning five APs in close proximity causes co-channel interference (CCI) due to excessive cell overlap.
  3. C
    Assigning channels 3 and 8 forces the access points to automatically revert connected 802.11ax clients to APIPA addressing due to DHCP relay frame encapsulation failure across overlapping frequencies.
  4. D
    The presence of channels 3 and 8 forces all access points on the ceiling line to disable WPA3-Enterprise 802.1X RADIUS authentication and fall back to open pre-shared key (PSK) mode.

Cevap

Channels 3 and 8 overlap with adjacent channels 1, 6, and 11, causing severe adjacent-channel interference (ACI) and frame corruption because overlapping signals cannot be decoded or coordinated by CSMA/CA.
The correct option highlights that in the 2.4 GHz band, each 20 MHz channel overlaps with adjacent channel numbers due to 5 MHz center-frequency spacing. The only non-overlapping 3-channel plan in North America uses channels 1, 6, and 11. Inserting channels 3 and 8 creates adjacent-channel interference (ACI), which disrupts CSMA/CA carrier sensing and leads to high packet corruption and retries.

Adım Adım Çözüm

1
Analyze the frequency structure of the 2.4 GHz Wi-Fi spectrum.
Each standard 802.11 2.4 GHz channel occupies 20 MHz of bandwidth, but channel center frequencies are spaced only 5 MHz apart.
Understanding channel width vs channel spacing establishes why channels 1, 6, and 11 are the only 3 non-overlapping 20 MHz channels in North America.
2
Evaluate the impact of assigning channels 3 and 8 alongside channels 1, 6, and 11.
Channel 3 overlaps partially with both channel 1 and channel 6. Channel 8 overlaps partially with both channel 6 and channel 11.
Partial spectral overlap prevents wireless stations from correctly decoding preambles from adjacent APs, causing CSMA/CA clear channel assessment (CCA) to treat the overlapping energy as non-Wi-Fi noise/interference rather than manageable Wi-Fi frames.
3
Differentiate between Co-Channel Interference (CCI) and Adjacent-Channel Interference (ACI).
CCI allows devices to share airtime via CSMA/CA backoff algorithms, whereas ACI causes raw signal collision, uncoordinated interference, high bit error rates, and severe throughput collapse.
This confirms that introducing channels 3 and 8 creates destructive ACI rather than manageable CCI.

Anahtar Kavram

2.4 GHz Non-Overlapping Channel Planning and Adjacent-Channel Interference (ACI)
Tahmini Süre:2m 0s
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Wireless Network Deployment and Standards

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