24-02-2012, 03:32 PM
Local Area Networks
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INTRODUCTION
Local Area Networks have evolved over the past 20 or so years to become a
crucial ingredient in the success of businesses, large and small. From the smallest
office to the largest multinational corporation shared access to information resources
is an indispensable part of modern business processes. Local Area Networks (LAN)
have been traditionally connected with wired infrastructure and a multi-billion dollar
industry has grown up to supply customers needs for wired networking products.
Companies like Cisco, 3Com, Bay Networks and Cabletron have developed a vast
range of products to implement and manage Local Area Networks of all sizes and to
interconnect them throughout the enterprise. Over the past ten or so years an
alternative to wired LAN structures has evolved in the form of the Wireless LAN
(WLAN). In a manner analogous to the growth of the wired LAN, initial application
and market success of the WLAN was in specialized, vertical markets.
STANDARDS
Symbol has been a leader in establishing wireless standards—for
interoperability, Multimedia transmission, and international connectivity. Our
engineers sit on the committees of a number of trade organizations dedicated to
creating and implementing these standards. Following are the key wireless
technology standards in use today. Check the Glossary for full explanations of each
standard:
NETWORK
IEEE 802.11 Architectures
In IEEE's proposed standard for wireless LANs (IEEE 802.11), there are two
different ways to configure a network: ad-hoc and infrastructure.
AD-HOC Network
In the ad-hoc network, computers are brought together to form a network "on
the fly." As shown in Figure 1, there is no structure to the network; there are no fixed
points; and usually every node is able to communicate with every other node. A
smallest Wireless LAN may consist of computers each equipped with wireless n/w
interface card.
