... FHSS does not support data rates greater than 2 Mbps it is not used in the IEEE standard, 802.11b. The DSSS (direct-sequence spread-spectrum): This method allows for much higher data rates by dividing the 2.4-GHz band into 14 22 MHz channels. In DSSS, the data is encoded into redundant bit patterns, or "chips." When a chip is transmitted, the total power of the DSSS signal is spread across one of the 22-MHz channels .The chip encoding and spread-spectrum techniques provide data redundancy in DSSS radios. The 1 Mbps DSSS data rate uses BPSK (binary-phase-shift-keying) modulation. The 2-Mbps data uses QPSK (quadrature-phase-shift-keying) modulation. The 802.llb standard also uses QPSK modulation for the 5.5- and 11-Mbps data rates, but it uses a more sophisticated encoding technique, CCK (complementary-code keying), that increases a radio receiver's ability to distinguish encoded bits in the presence of interference. When interference or range becomes too great ...

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