Resolution
Roaming is a process controlled by the client adapter and is not defined by IEEE standards. This is also vendor-specific since each vendor has its own roaming algorithms. The roaming functionality is based on signal quality, not proximity. When a client's signal quality drops, it roams to another access point.
For the roaming process to occur adjacent access point's coverage cells should overlap to the maximum of 20 - 30 % above which it causes interference.
For more information about roaming,
Problem Type
Configure / Configuration issues
Technical product specification / features
Products
WLAN adapters (wireless card) / ACU (Aironet Client Utility)
Autonomous Access Points
Topology
Wireless client to AP
SW Features
Roaming