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part of the LAN. A wireless LAN may be further connected to a more extensive
fixed network such as LAN, WAN, the Internet, etc. The primary component of a wireless LAN is the wireless interface card that has an antenna. This interface card
can be connected to the mobile unit as well as to the fixed network. Wireless
LANs have limited range and are designed to be used only in local environments
such as a building, hallway, park, or office complex. The main advantage is the
flexibility and mobility supported by a wireless LAN; bandwidth considerations
Unlike cellular networks with allocated channels (frequencies), users in WLANs
have to share frequencies, which may eventually lead to collisions. The choice of
frequency depends on whether microwave, spread-spectrum, or infrared
communication will be used. Interference and security depend on the type of
communications method used in the WLAN.
The following three are the primary WLAN standards:
IEEE 802.11. The IEEE 802.11 standard supports 1 Mbps data rate and
several choices of physical medium such as spread spectrum and infrared. It also
supports prioritized access to the medium. An additional feature of this standard is
battery conservation for inactive or idle wireless users. Many universities and
companies are encouraging the use of IEEE 802.11-based LANs for accessing
campus computing systems and the Internet. The IEEE 802.11 standard is being
enhanced to support 11 Mbps data rate.
HiperLAN. The HiperLAN standard can be used to support 23.5 Mbps
channel rates. It, however, allows the use of only spread spectrum physical
medium. Like IEEE 802.11, it also supports prioritized access to the medium.
3. HiperLAN2. Another emerging WLAN standard is HiperLAN2, which is
being standardized by ETSI (European Telecommunications Standard Institute).
An exciting feature of this standard is that it provides for use of connections that
offer different quality of service for different applications. It uses time-division
multiplexing of unicast, multicast, and broadcast connections. Many major players
in the WLAN area have formed HiperLAN2 Global Forum to advance and
complement the ETS1 standardization process.
Wireless Local Loops (WLLs)
Wireless Local Loops (WL...
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This document was uploaded on 04/07/2014.
- Spring '14