Wireless LANs are deployed in an access layer role, meaning that they are used as an entry point into a wired network. The following figure illustrates mobile clients gaining access to a wired network through a connection device (access point).
Network Extension
Wireless LANs can be easily implemented to provide seamless connectivity to remote areas within a building, as illustrated by the floor plan image in the following. Because little wiring is necessary to install a wireless LAN, the costs of hiring installers and purchasing Ethernet cable might be completely eliminated.
Building-to-Building Connectivity
There are two different types of building-to-building connectivity. The first is called point-to-point (PTP), and the second is called point-to-multipoint (PTMP). Point-to-point links are wireless connections between only two buildings, as illustrated in the following figure. PTP connections almost always use semi-directional or highly-directional antennas at each end of the link.
Last Mile Data Delivery
"Last mile" refers to the communication infrastructure—wired or wireless—that exists between the central office of the telecommunications company (telco) or cable company and the end user. Currently the telcos and cable companies own their last mile infrastructure, but with the broadening interest in wireless technology, WISPs are now creating their own wireless last mile delivery service, as illustrated in the following figure.
MobilityAs an access layer solution, wireless LANs cannot replace wired LANs in terms of data rates (100BT at 100Mbps versus IEEE 802.11a at 54Mbps). What wireless LANs do offer is an increase in mobility (as can be seen in the following figure) as the trade off for speed and quality of service.
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