Patent ID: 8050230

Claim:
A method of triggering handoff of a roaming mobile station from a serving BSS to a candidate BSS for VoWLAN communication, comprising the steps of: continuously monitoring link qualities of the serving BSS and the candidate BSS; generating and updating a list of candidate BSSs for handoff; selecting a candidate BSS for handoff and completing pre-authentication of the roaming mobile station with a selected best candidate BSS; triggering the handoff when the link quality of the serving BSS becomes lower by a predetermined amount than the link quality of the selected candidate BSS; using a roaming controller for performing scanning and said monitoring functions, wherein said roaming controller performs a static keep alive function to maintain pre-authentication with said selected candidate BSS as the best candidate BSS, and wherein said roaming controller chooses a scanning functionality comprising: using a fast scanning functionality by scanning only frames received from the best candidate BSS if the link quality of the serving BSS decreases and the link quality of the best candidate BSS increases while roaming; and using a normal scanning functionality to reselect the best candidate BSS if the link quality of the serving BSS decreases and the link quality of the best candidate BSS decreases while roaming; and interrupting the scanning temporarily if no candidate BSS is immediately found before scanning resumes, wherein no scanning occurs for a defined inter-scanning maximum period.