VoWLAN handoff quality is fundamentally determined by the AP placement strategy relative to the direction of user movement. When a user is in motion carrying an active voice call, the roaming event must occur before signal quality degrades below the minimum acceptable VoWLAN threshold (typically -67 dBm for voice, with a minimum SNR of 25 dB). This requires the user to encounter increasing signal strength from a neighboring AP before the current AP ' s signal drops below the threshold. The optimal AP placement follows the principle of overlapping coverage along the predicted path of travel — APs must be positioned so that as a user moves, they progressively enter the coverage zone of the next AP while still within adequate range of the current one. Floor plan B represents the correct design where APs are positioned along the travel path with sufficient cell overlap (typically 15-20%) to ensure seamless 802.11r fast BSS transitions. Incorrect floor plans place APs perpendicular to travel direction, at path endpoints only, or with insufficient overlap zones — all of which create roaming dead zones where the handoff occurs too late, causing voice call disruption. Reference: WLSD Study Guide — VoWLAN AP Placement, Roaming Design for Moving Users, Cell Overlap and Fast Transition Planning.