OFDM
DSSS spreads the chips of a single data stream into one wide 22 MHz channel. It is inherently limited to an 11 Mbps data rate because of the consistent 11-MHz chipping rate that feeds into the RF modulation. To scale beyond that limit, a vastly different approach is needed.
In contrast, orthogonal frequency division multiplexing (OFDM) sends data bits in parallel over multiple frequencies, all contained in a single 20 MHz channel. Each channel is divided into 64 subcarriers (also called subchannels or tones) that are spaced 312.5 kHz apart. The subcarriers are broken down into the following types:
Guard—12 subcarriers are used to help set ...
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