802.11a Frequency Band — Choose the correct range Which frequency band does IEEE 802.11a use for wireless LAN operation?

Introduction / Context:
Different Wi-Fi amendments operate in different bands, which impacts channel availability, interference, and propagation. 802.11a was the first widely used OFDM-based Wi-Fi at higher frequencies than 2.4GHz, providing more non-overlapping channels but shorter range through obstacles.

Given Data / Assumptions:

• We are choosing the correct frequency band, not throughput.
• 802.11a uses OFDM with 20MHz channels in 5GHz UNII bands.
• Units matter: GHz (frequency) vs. Gbps (throughput).

Concept / Approach:
802.11a operates exclusively in the 5GHz band. Confusions often arise because 802.11g also reaches 54Mbps but at 2.4GHz. Options that say “Gbps” are unit traps (throughput units), not frequency. Selecting the 5GHz option identifies the correct band for 802.11a.

Step-by-Step Solution:
Recall mapping: 802.11b/g → 2.4GHz; 802.11a → 5GHz.Ignore options with Gbps (throughput unit, not frequency).Choose 5GHz as the correct band.

Verification / Alternative check:
Any Wi-Fi quick reference shows 802.11a: 5GHz, 54Mbps max PHY (legacy), 12+ channels depending on regulatory domain.

Why Other Options Are Wrong:

• 2.4GHz: That is 802.11b/g (and 802.11n can use both bands).
• Gbps answers: Wrong units; they denote data rates, not RF frequency.
• 900MHz: Not an 802.11a band.

Common Pitfalls:
Mixing up 802.11a and 802.11g because both show 54Mbps; band (5GHz vs. 2.4GHz) is the differentiator.

Final Answer:
5GHz