Roaming aggressiveness is the threshold for that decision. Think of it like the thermostat in your house:
Imagine a cubicle farm. Every 20 feet, there is an AP. At Level 5, your laptop sees AP A at -55 dBm and AP B at -58 dBm. It roams to B. Two seconds later, it sees AP A at -57 dBm and AP B at -60 dBm. It roams back to A. This cycle repeats indefinitely.
Most network adapters, particularly those from Intel , offer five distinct levels: