In WLAN networks, how many microseconds is the GI fixed in the 802.11a/b/g standard?

Question

Options

• A3.2
• B0.4
• C0.8
• D1.6

• A
  8% (4)
• B
  13% (7)
• C
  4% (2)
• D
  75% (39)

Explanation

Option D (1.6 μs) appears to conflict with the IEEE 802.11a/g specification - this may be an error in the exam question. In the 802.11a/g standard, the Guard Interval for OFDM is fixed at 0.8 μs (800 nanoseconds), making C the technically correct answer per the published standard.

Here is what each value actually represents in the 802.11 family:

• 3.2 μs (A) - the useful data symbol duration in 802.11a/g OFDM, not the GI
• 0.4 μs (B) - the Short Guard Interval (SGI) option introduced in 802.11n/ac; not available in 802.11a/b/g
• 0.8 μs (C) - the actual GI defined in 802.11a/g (total OFDM symbol = 3.2 + 0.8 = 4 μs)
• 1.6 μs (D) - a GI option introduced in 802.11ax (Wi-Fi 6), not 802.11a/b/g

Memory tip: For 802.11a/g OFDM, remember "3.2 + 0.8 = 4" - data portion is 3.2 μs, guard interval is 0.8 μs, total symbol is 4 μs. If your exam marks D as correct, I'd recommend verifying against your course textbook, as this may be a question error.

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