Throughput of legacy Wi-Fi: What is the maximum data rate defined by the IEEE 802.11a standard?

Introduction / Context:
Legacy Wi-Fi standards have headline data rates that are frequently referenced in certification exams and design discussions. 802.11a introduced OFDM at 5 GHz with a maximum PHY rate of 54 Mbps per 20-MHz channel.

Given Data / Assumptions:

• PHY data rate, not real-world throughput.
• Single 20-MHz channel, standard 11a modulation and coding.

Concept / Approach:
802.11a’s OFDM supports multiple rates: 6, 9, 12, 18, 24, 36, 48, and 54 Mbps, with 54 Mbps being the top PHY rate under ideal conditions.

Step-by-Step Solution:

Verification / Alternative check:
Standards summaries and vendor datasheets consistently list 54 Mbps as the maximum 802.11a rate.

Why Other Options Are Wrong:

• 6/11/22 Mbps: Valid in other contexts (e.g., 802.11b 11 Mbps, PBCC 22 Mbps) but not the 11a maximum.
• 108 Mbps: Vendor “turbo” or channel bonding marketing, not standard 11a.

Common Pitfalls:
Confusing PHY rates with application throughput; mixing 11a with 11b/g figures.

Final Answer:
54 Mbps