802.11a standard provides wireless LAN bandwidth of up to 54Mbps in the 5GHz frequency spectrum. The 802.11a standard also uses orthogonal frequency division multiplexing (OFDM) for encoding rather than FHSS or DSSS.
802.11b standard provides for bandwidths of up to 11 Mbps (with fallback rates of 5.5, 2, and 1 Mbps) in the 2.4G Hz frequency spectrum. This standard is also called Wi-Fi or 802.11 high rates. The 802.11b standard uses only DSSS for data encoding.
802.11g standard provides for bandwidths of 20 Mbps+ in the 2.4 GHz frequency spectrum. This offers a maximum rate of 54 Mbps and is backward compatible with 802.11b.
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