User's Manual

ezWAVE Access Point Users’ Guide Version 1.6

Page 9 of 50

When an 802.11 client enters the range of one or more APs, it chooses an access point

to associate with (also called joining a Basic Service Set), based on signal strength and

observed packet error rates. Once accepted by the access point, the client tunes to the

radio channel to which the access point is set. Periodically it surveys all 802.11 channels

in order to assess whether a different access point would provide it with better

performance characteristics. If it determines that this is the case, it re-associates with the

new access point, tuning to the radio channel to which that access point is set. Re-

association usually occurs because the wireless station has physically moved away from

the original access point, causing the signal to weaken. In other cases, Re-association

occurs due to a change in radio characteristics in the building, or due simply to high

network traffic on the original access point. In the latter case this function is known as

“load balancing,” since its primary function is to distribute the total WLAN load most

efficiently across the available wireless infrastructure. This process of dynamically

associating and re-associating with APs allows network managers to set up WLANs with

very broad coverage by creating a series of overlapping 802.11b cells throughout a

building or across a campus. To be successful, the IT manager ideally will employ

“channel reuse,” taking care to set up each access point on an 802.11 DSSS channel

that does not overlap with a channel used by a neighboring access point.

Figure 3. Roaming

Backbone Network

Access Point (AP)

Inter-Cell Roaming