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Zorluk: ZorWireless Networking Standards and Technologies

During a post-installation survey of a retail facility's 2.4 GHz wireless infrastructure, a systems specialist discovers high frame retry rates caused by adjacent-channel interference. The site survey reveals that three neighboring access points are currently operating on channels 2, 5, and 8 with a 20 MHz channel width. Which channel configuration plan should the specialist implement to ensure that all three access points operate without adjacent-channel overlap?

  1. Channels 1, 6, and 11Cevap
  2. B
    Channels 1, 5, and 9
  3. C
    Channels 2, 6, and 10
  4. D
    Channels 3, 7, and 11

Cevap

Configuring Channels 1, 6, and 11 provides three distinct 20 MHz channels in the 2.4 GHz spectrum without adjacent-channel overlap.
In the 2.4 GHz band (operating from 2.400 GHz to 2.4835 GHz), channels are spaced 5 MHz apart, but a standard 802.11 channel consumes 20 MHz of bandwidth (22 MHz RF footprint). Consequently, a minimum of 25 MHz (5 channel numbers) of separation between center frequencies is required to prevent frequency overlap. The combination of Channels 1, 6, and 11 provides the maximum available three non-overlapping channels for multi-AP deployments in standard 1-11 channel regulatory domains.

Adım Adım Çözüm

1
Analyze the 2.4 GHz channel structure and bandwidth.
Each 20 MHz channel requires a 22 MHz spectral footprint (or 20 MHz channel bandwidth with guard bands), spanning 5 channel spacing increments of 5 MHz each.
Understanding channel width is required to compute frequency separation between neighboring access points.
2
Evaluate the distance required between center frequencies to prevent adjacent-channel interference.
A minimum spacing of 5 channel numbers (25 MHz) is required between center frequencies to prevent frequency band overlap.
Adjacent-channel interference occurs when overlapping frequencies distort transmitted signals.
3
Identify the standard non-overlapping channels in the 2.4 GHz ISM band for North American regulatory domains.
Channel 1 (2412 MHz), Channel 6 (2437 MHz), and Channel 11 (2462 MHz) are spaced 25 MHz apart and operate without any mutual overlap.
Using channels 1, 6, and 11 eliminates adjacent-channel interference completely across three adjacent coverage cells.

Anahtar Kavram

2.4 GHz Wireless Non-Overlapping Channels
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Wireless Networking Standards and Technologies

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