Complementary Code Keying (CCK) is a modulation technique deployed in wireless local area networks (WLANs) that follow IEEE 802.11b specification. CCK came into use in 1999 whereby it replaced the Barker code in wireless networks. CCK helps in attaining data rates higher than 2 Mbps, though at the cost of shorter ranges.
CCK is used in wireless LANs to attain theoretical maximum data rates of 11 Mbps.
CCK is implemented for transmission in the radio frequency range (RF band) of 2.4GHz – 2.4835GHz.
CCK includes a pair of codes called chipping sequences which are complementary to each other. In complementary codes, the number of pairs of identical elements, called like elements, in one sequence is equal to the number of pairs of unlike elements in the other sequence having same separation.
CCK has a shorter chipping sequence of 8 bits compared to the 11 bits chipping sequence of Barker Code. This results in less spreading and consequently higher data rates.
However, while using CCK, the signal becomes prone to narrowband interference and so its transmission range becomes shorter.