802.11 DSSS
In order to achieve high-speed wireless data networking, 802.11 was created
to foster interoperability between various brands of WLANs. The
goal was to create a “universal technology” that was platform independent
and both provided higher performance and interoperability using
products from different vendors. This permits wireless users to use any
hardware solution mix necessary to satisfy application requirements.
Standardization
Making 802.11 an industry standard provides for a decreased component
cost for users so that you can implement a WLAN cost effectively.
The 802.11 standard permits you to choose equipment that offers direct
sequence spread spectrum (DSSS) or frequency hopping spread spectrum
(FHSS), both based on radio frequency (RF) transmissions.
802.11 started out by having DSSS support different physical layers
(PHY) at a 2-Mbps peak data rate that can fall back to 1 Mbps in very
noisy areas. FHSS PHY functions at 1 Mbps and permits 2 Mbps in
open environments without any interference.
The evolution of 802.11 allowed the implementation of DSSS at higher
data transmission rates of 11 Mbps, making the transition from the
2-Mbps 802.11 DSSS system to a system at 11 Mbps simple because the
modulation methods are analogous. In fact, 2-Mbps DSSS systems will
operate alongside 11-Mbps 802.11 systems to provide a seamless transition
between lower and higher rates of data transmission. This is much
the same as moving from 10-Mbps to 100 Mbps wired Ethernet in an
effort to allow greater performance enhancements without having to
revamp the entire protocol to make things work together.
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