Complementary Code Keying
max CCK = 11 Mbps 4 Msymbol/s QPSK like symbols spread by 8 chip due to adjacent chan. interference.

For faster rates, CCK is used to transmit the packet preamble/header and OFDM is used to transmit the payload up to 54 Mbps. The header contains the payload length, so all other receivers know to keep quiet during transmission to prevent direct collisions. They also use RTS/ CTS packets so units far from each other hear the shared router control packets.

There are many design block diagrams on how they radios work on the web.