DSSS PMD Operation

 
DSSS PMD Operation
The operation of the DSSS PMD translates the binary representation of the PPDUs into a radio
signal suitable for transmission. The DSSS Physical layer performs this process by multiplying
a radio frequency carrier by a pseudo-noise (PN) digital signal. The resulting signal appears as
noise if plotted in the frequency domain. The wider bandwidth of the direct sequence signal
enables the signal power to drop below the noise threshold without loss of information.
As with FHSS, the DSSS Physical layer operates within the 2.4GHz to 2.4835GHz frequency
range, depending on regulatory authorities in different parts of the world. The 802.11 standard
specifies operation of DSSS on up to 14 channels of different frequencies (see Table 5.1).
Channels are each 22MHz wide.