IEEE 802.11b

  This is a wireless communication protocol to work in 2.4 GHz ISM (Industrial, Scientific & Medical) band. This is  a   "Licence Free" frequency band; & leads to cost-effective wireless links. This uses three physical layers (PHY) - DSSS (Direct Sequence Spread Spectrum) , FHSS (Frequency Hopping Spread Spectrum) & IR (Infra Red).  In DSSS there are 14 frequency channels defined, each separated by 5 MHz & spectrum of each occupying a BW of 22 MHz.