SSID broadcasts can be disabled on the access point, but this approach does not work
if the client needs to see the SSID in the beacon.
Figure 3-9 BSA Topology
If a single cell does not provide enough coverage, any number of cells can be added to
extend the range. This range is known as an Extended Service Area (ESA). Figure 3-10
shows an ESA topology.
It is recommended that ESA cells have 10 to 15 percent overlap to allow remote users to
roam without losing RF connections. For wireless voice networks, an overlap of 15 to
20 percent is recommended. Bordering cells should be set to different nonoverlapping
channels for best performance.
Wireless Topology Data Rates
WLAN clients have the ability to shift data rates while moving. This strategy allows the
same client operating at 11 Mbps to shift to 5.5 Mbps, then 2 Mbps, and ?¬?nally still
communicate in the outside ring at 1 Mbps. This rate-shifting happens without losing the
connection and without any interaction from the user. Rate-shifting also happens on a
transmission-by-transmission basis; therefore, the access point has the ability to support
multiple clients at multiple speeds depending upon the location of each client. Figure 3-11
shows data rates at different distances from the access point.
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