ZyXEL Communications VANTAGE RADIUS 50 User Manual page 130

Vantage RADIUS User's Guide
standard was developed to maximize interoperability between differing brands of wireless LANs
as well as to introduce a variety of performance improvements and benefits.
The IEEE 802.11 specifies three different transmission methods for the PHY, the layer
responsible for transferring data between nodes. Two of the methods use spread spectrum RF
signals, Direct Sequence Spread Spectrum (DSSS) and Frequency-Hopping Spread Spectrum
(FHSS), in the 2.4 to 2.4825 GHz unlicensed ISM (Industrial, Scientific and Medical) band. The
third method is infrared technology, using very high frequencies, just below visible light in the
electromagnetic spectrum to carry data.
Ad-hoc Wireless LAN Configuration
The simplest WLAN configuration is an independent (Ad-hoc) WLAN that connects a set of
computers with wireless nodes or stations (STA), which is called a Basic Service Set (BSS). In
the most basic form, a wireless LAN connects a set of computers with wireless adapters. Any
time two or more wireless adapters are within range of each other, they can set up an independent
network, which is commonly referred to as an Ad-hoc network or Independent Basic Service Set
(IBSS). See the following diagram of an example of an Ad-hoc wireless LAN.
E-2 Wireless LAN and IEEE 802.11