OFDM is a modulation method that divides the channel bandwidth into multiple subcarriers, each

carrying a single data symbol. This allows for higher data rates and more robust transmissions in

multipath environments. OFDM was first introduced in the 802.11a standard, which operates in the 5

GHz band and supports data rates up to 54 Mbps. Later, the 802.11g standard adopted OFDM for the

2.4 GHz band, and the 802.11n and 802.11ac standards enhanced OFDM with features such as MIMO

(Multiple Input Multiple Output), channel bonding, and higher-order modulation schemes to achieve

data rates up to 600 Mbps and 6.9 Gbps, respectively. These standards are collectively known as the

ERP (Extended Rate PHY), HT (High Throughput), and VHT (Very High Throughput) PHYs

. Reference: [CWNA-109 Study Guide], Chapter 4: Radio Frequency Signal and Antenna Concepts,

page 163; [CWNA-109 Study Guide], Chapter 4: Radio Frequency Signal and Antenna Concepts, page

157.