ZyXEL Communications B-2000 User Manual
ZyAIR B-2000 Wireless LAN Gateway with 4-Port Switch
Wireless LAN and IEEE 802.11
A
Appendix A
Wireless LAN and IEEE 802.11
A wireless LAN (WLAN) provides a flexible data communications system that you can use to access
various services (navigating the Internet, email, printer services, etc.) without any expensive network
cabling infrastructure. In effect a wireless LAN environment provides you the freedom to stay connected to
the network while in the coverage area.
various services (navigating the Internet, email, printer services, etc.) without any expensive network
cabling infrastructure. In effect a wireless LAN environment provides you the freedom to stay connected to
the network while in the coverage area.
Benefits of a Wireless LAN
1. Access to network services in areas otherwise hard or expensive to wire, such as historical buildings,
1. Access to network services in areas otherwise hard or expensive to wire, such as historical buildings,
buildings with asbestos materials and classrooms.
2. Doctors and nurses can access a complete patient’s profile on a handheld or notebook computer upon
entering a patient’s room.
3. It allows flexible workgroups a lower total cost of ownership for networks that are frequently
reconfigured.
4. Conference room users can access the network as they move from meeting to meeting- accessing up-to-
date information that facilitates the ability to communicate decisions “on the fly”.
5. It provides campus-wide networking coverage, allowing enterprises the roaming capability to set up
easy-to-use wireless networks that transparently covers an entire campus.
IEEE 802.11
The 1997 completion of the IEEE 802.11 standard for wireless LANs (WLANs) was a first important step
in the evolutionary development of wireless networking technologies. The standard was developed to
maximize interoperability between differing brands of wireless LANs and to introduce a variety of
performance improvements and benefits. On September 16, 1999, the 802.11b provided much higher data
rates of up to 11Mbps, while maintaining the 802.11 protocol.
in the evolutionary development of wireless networking technologies. The standard was developed to
maximize interoperability between differing brands of wireless LANs and to introduce a variety of
performance improvements and benefits. On September 16, 1999, the 802.11b provided much higher data
rates of up to 11Mbps, while maintaining the 802.11 protocol.
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.
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
with wireless nodes or stations (STA), which is called a Basic Service Set (BSS). In the most basic form, a