WLAN Configurations
Independent WLANs
The simplest WLAN configuration is an independent (or peer-to-peer) WLAN that connects a set of PCs with wireless adapters. Any time two or more wireless adapters are within range of each other, they can set up an independent network (Figure 3). These on-demand networks typically require no administration or preconfiguration.
Figure 3.
Independent WLAN
Access points can extend the range of independent WLANs by acting as a repeater (see Figure 4), effectively doubling the distance between wireless PCs.
Figure 4. Extended-Range Independent WLAN Using Access Point as Repeater
Infrastructure WLANs
In infrastructure WLANs, multiple access points link the WLAN to the wired network and allow users to efficiently share network resources. The access points not only provide communication with the wired network but also mediate wireless network traffic in the immediate neighborhood. Multiple access points can provide wireless coverage for an entire building or campus.
Figure 5. Infrastructure WLAN
Microcells and Roaming
Wireless communication is limited by how far signals carry for given power output. WLANs use cells, called microcells, similar to the cellular telephone system to extend the range of wireless connectivity. At any point in time, a mobile PC equipped with a WLAN adapter is associated with a single access point and its microcell, or area of coverage. Individual microcells overlap to allow continuous communication within wired network. They handle low-power signals and &#atilde;hand off&#atilde; users as they roam through a given geographic area.
Figure 6. Handing off the WLAN Connection Between Access Points
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