Wireless LAN users are sometimes concerned when a client device stays associated to a distant access point instead of roaming to a closer access point. However, if a client signal to a distant access point remains strong and the signal quality is high, the client will not roam to a closer access point. Checking constantly for closer access points would be inefficient, and the extra radio traffic would slow throughput on the wireless LAN.
The client driver makes the decision to chose the AP or the signal based on its own protocols or the rules.. eg - some of the client drivers tries to search the signal from the one which it was previously connected to.. or something like that.. however most of the client drivers choses the one which has the best signal strength..
