Network Allocation Vector (NAV) and "beam access control" (BAC) techniques are provided to address data collision problems in WLANs wherein APs provide wireless network access in a service area defined by multiple sectors via use of a switchable antenna system or the like. Preferably, every time the AP visits a sector and before the AP moves on to the next sector, the AP can set the NAV equal to the time it will take until its next visit. Alternatively, or in addition, a BAC bit is transmitted by an AP to control access to the AP by WTRUs disposed in a service sector in which the BAC is transmitted.