IEEE wireless local area network
802.11b is capable of 11 Mbps
, which happens to be faster than my school's wired LAN. Products conforming to 802.11b have a maximum range of about 1650 feet (503 meters) outdoors, but at this range, the bandwidth usually drops to about 1 Mbps (still great if you're just using the Internet). Indoors, at the full 11 Mbps, range is approximately 150 feet (46 meters).
This standard runs on the 2.4GHz
frequency range. 802.11b uses direct sequence spread spectrum (DSSS
). At high data rates, DSSS uses a set of 64, 8-bit codewords (Complementary Code Keying (CCK
). These codewords are recognizable even in the presence of significant interference. To compensate for range and noise variation, it can dynamically shift between 1, 2, 5.5, and 11 Mbps.
Actual operation at the Data Link Layer
of the OSI Reference Model
is very similar to IEEE 802.3
, with the addition of some additional functionality for wireless.
Wireless networks can operate in a variety of modes. The first is Ad-hoc, which creates a wireless network from client stations. These stations do not tie into a larger network and no base station
is needed. In Infrastructure
mode, the wireless clients communicate with a base station or access point, that may be connected to a wired LAN or the Internet. Basic mode uses only one base sation; extended allows for roaming
between multiple base stations.
802.11b also encludes Layer 1 and Layer 2 security functionality. Wired Equivalant Privacy (WEP
) uses a extended session identity that wireless clients must know in order to connect to it (if enabled). Keys are RC4
; in either 64 or 128-bit
flavors. Keys for the client and base station must match in order for a client to associate and gain access to a base station. The WEP security is relatively weak, and additional security should be used for any businesses installing a wireless LAN.