Wireless Radio Standard

The 802.11 standard offers two distinct types of PHY, including two RF
technologies designated as:


Direct-sequence spread spectrum (DSSS)


Frequency-hopped spread spectrum (FHSS)
The 802.11b standard in both DSSS and FHSS PHY designations is
created to satisfy FCC regulations to operate in the 2.4 GHz ISM band.
This radio spectrum for the 802.11b standard is allocated differently for
every section of the world. The radio spectrum is designed as follows:

Country Frequency Spectrum
United States 2.4000–2.4835 GHz
Europe 2.4000–2.4835 GHz
Japan 2.471–2.497 GHz
France 2.4465–2.4835 GHz
Spain 2.445–2.475 GHz

FHSS and DSSS PHYs support both 1 and 2 Mbps. DSSS systems
employ the same type of radio transmission as GPS systems and satellite
telephones. Note that each information bit is linked through an XOR
function that has an increased pseudorandom numerical (PN) sequence,
which results in a higher speed digital stream modulated on a carrier
frequency through differential phase shift keying (DPSK).