There are many standards of modulation. The following are some of the most commonly used types.
DSSS DSSS (Direct-Sequence Spread Spectrum) is a transmission technology that combines the data signal with a higher data rate bit sequence called a chipping code. This improves noise resistance and data integrity.
OFDMOFDM (Orthogonal Frequency Division Multiplexing) transmits digital data over a radio wave by splitting a radio signal into multiple sub-signals. These are then transmitted simultaneously at different frequencies. This modulation technique reduces the amount of crosstalk in signal transmissions.
CCK CCK (Complementary Code Keying) uses a set of 64 eight-bit code words to encode data for 5.5 and 11Mbps data rates in the 2.4GHz band of 802.11b standard. The code words have unique mathematical properties. This allows them to be correctly distinguished from one another by a receiver even in the presence of substantial noise and interference.
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