Graphics - Courtesy Intel
& Symbol websites
Wireless LAN-based mobile computing solutions are becoming
quite prevalent in many horizontal applications in the general office and vertical
industries, such as health care (hospitals), manufacturing, goods distribution in a
warehouse, stock-trading on the stock exchange floor, hospitality (restaurants), and
retail. Here are important but introductory facts about wireless LANs:
- Most wireless LANs operate in multiple frequency ranges -
unlicensed 902-928 ISM (industrial, Scientific and Medical) band,
unlicensed 2.4 GHz band and licensed 18-23 GHz
- There are two technologies used in wireless LANs - direct
sequence (DS) coding or frequency hopping (FH).
- Key hardware components of a wireless LAN are a wireless LAN
adapter along with an antenna that resides in the mobile computer device (notebook or PDA)
and an "Access Point" which acts as the hub and connects multiple mobile devices
to a server. You can realistically support only 10-30 mobile devices per access
point, depending on the network traffic.
- General distance range for coverage of wireless LANs is in 200
to 1000 feet depending on the type of walls, height of ceilings and existence of physical
obstructions. By having multiple access points that span a building floor, you
can support longer distances. Physical design of a wireless LAN should be done by
well-trained personnel who understand the technology and propagation of radio signals.
- First generation of wireless LANs supported
1-2 Mbps speed. However, during 2000, typical speed supported by IEEE
802.11 compatible wireless LAN adapters
increased to 11 Mbps.
- IEEE 802.11 is a recent (1998-99) standard for wireless
LANs. Many vendors (3COM, Lucent, Proxim) have started manufacturing products that meet this standard.
However, interoperability across vendors is still problematic and spotty. A LAN Interoperability forum has been established to improve
this. As of now, interoperability for 802.11 adapters is better with DS products than with FH products.
- There are two IEEE 802.11 standards - IEEE
802.11a and IEEE 802.11b. Oddly enough, the latter standard came before
the former standard. IEEE 802.11a standard operates in less-crowded 5
GHz band. However equipment conforming to IEEE 802.11a standard
will start appearing in fall of 2001. European version of IEEE 802.11a,
called HiperLAN2, will also ship in 2002. For more info on
HiperLAN2, go to www.hiperlan2.org.
- Vendors have been shipping 802.11b products
since late 1999.
- Both 802.11b Wireless LANs and Bluetooth
operate on 2.4 GHz band. Therefore, there is potential for interference
if you are using both technologies in close proximity.
- Prominent vendors in the wireless LAN arena are Proxim, Aironet
(now part of Cisco), Symbol, Intermec
, BreezeCOM, Xircom, Lucent, Ericsson and